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齋藤 勝晴  サイトウ カツハル

教員組織学術研究院(農学系)電話番号
教育組織農学部 農学生命科学科 植物資源科学コースFAX番号
職名教授メールアドレスsaitok(at)shinshu-u.ac.jp
住所〒399-4598 399-4598 長野県上伊那郡南箕輪村8304ホームページURLhttp://karamatsu.shinshu-u.ac.jp/lab/soil/index.htm

更新日:2024/02/21

プロフィール

兼担研究科・学部
大学院総合工学系研究科(博士課程) 生物・食料科学専攻 食資源生産学部門
総合理工学研究科(修士課程) 農学専攻 先端生命科学分野
研究分野
植物栄養学、土壌学
キーワード:菌根 , 共生 , 根粒 , 草地 , 植物栄養 , リン , 土壌
現在の研究課題
菌根形成に関わる宿主および菌側の遺伝子解析
キーワード:菌根共生 , 共生変異体 , RNA-seq解析 , 菌根形成に異常が見られるミヤコグサ変異体の遺伝学的解析。RNA-seqを用いた菌根形成に関わる遺伝子の同定。
アーバスキュラー菌根菌のリン酸輸送メカニズム
キーワード:菌根共生 , リン酸 , ポリリン酸 , 酸性ホスファターゼ , 電子顕微鏡 , ポリリン酸代謝やポリリン酸局在の解析を通して菌根菌から植物へのリン酸輸送を明らかにする。
アーバスキュラー菌根菌資材の開発
キーワード:胞子生産
所属学会
所属学会
The American Society of Plant Biologists
International Mycorrhiza Society
植物微生物研究会
菌根研究会
日本菌学会
日本植物生理学会
土壌微生物学会
日本草地学会
日本土壌肥料学会

所属学会役職担当
2023- , Soil Science and Plant Nutrition , Associate Editor-in-Chief
2022- , Microbes and Environments , Associate Editor
2022- , 日本草地学会誌 , 編集委員
2019- , 日本農学会 , 運営委員
2015- , Grassland Science , Editor
学歴
出身大学院
2001 , 東北大学 , 大学院農学研究科 , 環境修復生物工学専攻
1998 , 東北大学 , 大学院農学研究科 , 環境修復生物工学専攻

出身学校・専攻等(大学院を除く)
1996 , 東北大学 , 理学部 , 生物学科

取得学位
博士(農学) , 東北大学
修士(農学) , 東北大学
学士(理学) , 東北大学
受賞学術賞
2006 , 日本草地学会研究奨励賞(三井賞) , 草地生態系におけるアーバスキュラー菌根菌の動態に関する研究(第34号)
研究職歴等
研究職歴
2023- , 国立大学法人信州大学, 農学部, 教授
2006-2023 , 国立大学法人信州大学, 農学部, 准教授
2004-2006 , 独立行政法人科学技術振興機構 研究員
2003-2003 , OECDフェローシップ(カナダ・ゲルフ大学)
2002-2004 , 独立行政法人農業技術研究機構 特別研究員
2002-2002 , 生物系特定産業技術研究推進機構 派遣研究員

研究活動業績

研究業績(著書・
発表論文等)
書籍等出版物
根粒共生から菌根共生を探る, もっと菌根の世界
築地書館 2023(Sep. 22)
Author:齋藤勝晴


共生の生化学, 実践土壌学シリーズ 3「土壌生化学」, 99-116
朝倉書店 2019(Feb.)
Author:齋藤勝晴
Abstract:共生の生化学 朝倉書店


植物と菌根菌との共生, 食と微生物の事典, 406-407
朝倉書店 2017(Jul. 28)
Author:齋藤勝晴
Abstract:食と微生物の事典 朝倉書店


Phosphorus metabolism and transport in arbuscular mycorrhizal symbiosis, Molecular Mycorrhizal Symbiosis, 197-216
John Wiley & Sons 2016(Oct. 28)
Author:Saito Katsuharu; Ezawa Tatsuhiro
Abstract:Phosphorus metabolism and transport in arbuscular mycorrhizal symbiosis John Wiley & Sons, Inc.


アーバスキュラー菌根以外の菌根, 種生物学会編『共進化の生態学 : 生物間相互作用が織りなす多様性』, 261-263
文一総合出版 2008(Mar. 31)
Author:齋藤勝晴・川口正代司


アーバスキュラー菌根共生系から根粒共生系への進化, 種生物学会編『共進化の生態学 : 生物間相互作用が織りなす多様性』, 237-260
文一総合出版 2008(Mar. 31)
Author:斎藤勝晴・川口正代司


菌根菌、根粒菌、線虫との相互作用, プラントミメティックス -植物に学ぶ-, 531-535
エヌ・ティー・エス 2006(Aug.)
Author:斎藤勝晴・川口正代司
Abstract:「プラントミメティックス -植物に学ぶ-」 菌根菌、根粒菌、線虫との相互作用 エヌ・ティー・エス


草本類の共生微生物に関する調査法 菌根菌, 草地学実験調査法, 162-166
全国農村教育協会 2004(Mar.)
Author:斎藤勝晴・小島知子
Abstract:「草地学実験調査法」 草本類の共生微生物に関する調査法 菌根菌 全国農村教育協会


論文
Unveiling the tripartite synergistic interaction of plant-arbuscular mycorrhizal fungus symbiosis by endophytic Bacillus velezensis S141 in Lotus japonicus
Symbiosis 2024
Author:Sutee Kiddee; Jenjira Wongdee; Pongdet Piromyou; Pongpan Songwattana; Teerana Greetatorna; Nantakorn Boonkerd; Neung Teaumroong; Katsuharu Saito; Panlada Tittabutr


Polyphosphate polymerizing and depolymerizing activity of VTC4 protein in an arbuscular mycorrhizal fungus
Soil Science and Plant Nutrition,68(2):256-267 2022(Jan. 22)
Author:Nguyen, C.T., Ezawa, T., Saito, K.


Asymbiotic mass production of the arbuscular mycorrhizal fungus Rhizophagus clarus
Communications Biology,5(1):43 2022(Jan. 12)
Author:Tanaka, S., Hashimoto, K., Kobayashi, Y., Yano, K., Maeda, T., Kameoka, H., Ezawa, T., Saito, K., Akiyama, K., Kawaguchi, M.
Abstract:Abstract Arbuscular mycorrhizal (AM) symbiosis is a mutually beneficial interaction between fungi and land plants and promotes global phosphate cycling in terrestrial ecosystems. AM fungi are recognised as obligate symbionts that require root colonisation to complete a life cycle involving the production of propagules, asexual spores. Recently, it has been shown that Rhizophagus irregularis can produce infection-competent secondary spores asymbiotically by adding a fatty acid, palmitoleic acid. Furthermore, asymbiotic growth can be supported using myristate as a carbon and energy source for their asymbiotic growth to increase fungal biomass. However, the spore production and the ability of these spores to colonise host roots were still limited compared to the co-culture of the fungus with plant roots. Here we show that a combination of two plant hormones, strigolactone and jasmonate, induces the production of a large number of infection-competent spores in asymbiotic cultures of Rhizophagus clarus HR1 in the presence of myristate and organic nitrogen. Inoculation of asymbiotically-generated spores promoted the growth of host plants, as observed for spores produced by symbiotic culture system. Our findings provide a foundation for the elucidation of hormonal control of the fungal life cycle and the development of inoculum production schemes.


Role of cell wall polyphosphates in phosphorus transfer at the arbuscular interface in mycorrhizas
Frontiers in Plant Science,12:725939 2021(Sep.)
Author:Ngyuen, C. T., Saito, K.


Myristate can be used as a carbon and energy source for the asymbiotic growth of arbuscular mycorrhizal fungi
Proceedings of the National Academy of Sciences of the United States of America,117(41):25779-25788 2020(Oct. 13)
Author:Sugiura, Y., Akiyama, R., Tanaka, S., Yano, K., Kameoka, H., Marui, S., Saito, M., Kawaguchi, M., Akiyama, K., Saito, K.
Abstract:Proceedings of the National Academy of Sciences of the United States of America


Secretion compounds from Brevibacillus sp. SUT47 promote spore propagation of Acaulospora tuberculata colonizing maize roots (Zea mays L. cultivar Suwan 5)
ScienceAsia,46(5):634-634 2020
Author:Sutee Kiddee; Watcharin Yuttavanichakul; Nantakorn Boonkerd; Neung Teaumroong; Katsuharu Saito; Panlada Tittabutr


Stimulation of asymbiotic sporulation in arbuscular mycorrhizal fungi by fatty acids
Nature Microbiology,4(10):1654-1660 2019(Oct. 01)
Author:Hiromu Kameoka; Ippo Tsutsui; Katsuharu Saito; Yusuke Kikuchi; Yoshihiro Handa; Tatsuhiro Ezawa; Hideo Hayashi; Masayoshi Kawaguchi; Kohki Akiyama
Abstract:© 2019, The Author(s), under exclusive licence to Springer Nature Limited. Arbuscular mycorrhizal (AM) fungi are obligate symbionts that depend on living host plants to complete their life cycle1,2. This feature, which leads to their unculturability in the absence of plants, strongly hinders basic research and agricultural application of AM fungi. However, at least one AM fungus can grow and develop fertile spores independently of a host plant in co-culture with the bacterium Paenibacillus validus3. The bacteria-derived substances are thought to act as stimulants or nutrients for fungal sporulation, but these molecules have not been identified. Here, we show that (S)-12-methyltetradecanoic acid4,5, a methyl branched-chain fatty acid isolated from bacterial cultures, stimulates the branching of hyphae germinated from mother spores and the formation of secondary spores in axenic culture of the AM fungus Rhizophagus irregularis. Extensive testing of fatty acids revealed that palmitoleic acid induces more secondary spores than the bacterial fatty acid in R. irregularis. These induced spores have the ability to infect host plant roots and to generate daughter spores. Our work shows that, in addition to a major source of organic carbon6–9, fatty acids act as stimulants to induce infection-competent secondary spores in the asymbiotic stage and could provide the key to developing the axenic production of AM inoculum.


草地および飼料畑におけるアーバスキュラー菌根菌の生態と共生機能
日本草地学会誌,64(4):276-283 2019(Jan.)
Author:齋藤勝晴
Abstract:日本草地学会誌


Strigolactone Biosynthesis Genes of Rice are Required for the Punctual Entry of Arbuscular Mycorrhizal Fungi into the Roots
Plant and Cell Physiology,59(3):544-553 2018(Mar. 01)
Author:Yoshihiro Kobae; Hiromu Kameoka; Yusaku Sugimura; Katsuharu Saito; Ryo Ohtomo; Toru Fujiwara; Junko Kyozuka
Abstract:Arbuscular mycorrhiza (AM) is a mutualistic association between most plant species and the ancient fungal phylum Glomeromycota in roots, and it plays a key role in a plant's nutrient uptake from the soil. Roots synthesize strigolactones (SLs), derivatives of carotenoids, and exude them to induce energy metabolism and hyphal branching of AM fungi. Despite the well-documented roles of SLs in the pre-symbiotic phase, little is known about the role of SLs in the process of root colonization. Here we show that the expansion of root colonization is suppressed in the mutants of rice (Oryza sativa) SL biosynthesis genes, carotenoid cleavage dioxygenase D10 and more severely in D17. Interestingly, most of the colonization process is normal, i.e. AM fungal hyphae approach the roots and cling around them, and epidermal penetration, arbuscule size, arbuscule number per hyphopodium and metabolic activity of the intraradical mycelium are not affected in d10 and d17 mutants. In contrast, hyphopodium formation is severely attenuated. Our observations establish the requirement for SL biosynthesis genes for efficient hyphopodium formation, suggesting that SLs are required in this process. Efficient hyphopodium formation is required for the punctual internalization of hyphae into roots and maintaining the expansion of colonization.


How do arbuscular mycorrhizal fungi handle phosphate? New insights into fine-tuning of phosphate metabolism
New Phytologist,220:1119-1121 2018
Author:Ezawa, T. and Saito, K.
Abstract:New Phytologist


Stringent Expression Control of Pathogenic R-body Production in Legume Symbiont Azorhizobium caulinodans
mBio,8(4):e00715-17 2017(Jul.)
Author:Jun-ichi Matsuoka; Fumiko Ishizuna; Keigo Kurumisawa; Kengo Morohashi; Tetsuhiro Ogawa; Makoto Hidaka; Katsuharu Saito; Tatsuhiro Ezawa; Toshihiro Aono
Abstract:R bodies are insoluble large polymers consisting of small proteins encoded by reb genes and are coiled into cylindrical structures in bacterial cells. They were first discovered in Caedibacter species, which are obligate endosymbionts of paramecia. Caedibacter confers a killer trait on the host paramecia. R-body-producing symbionts are released from their host paramecia and kill symbiont-free paramecia after ingestion. The roles of R bodies have not been explained in bacteria other than Caedibacter. Azorhizobium caulinodans ORS571, a microsymbiont of the legume Sesbania rostrata, carries a reb operon containing four reb genes that are regulated by the repressor PraR. Herein, deletion of the praR gene resulted in R-body formation and death of host plant cells. The rebR gene in the reb operon encodes an activator. Three PraR binding sites and a RebR binding site are present in the promoter region of the reb operon. Expression analyses using strains with mutations within the PraR binding site and/or the RebR binding site revealed that PraR and RebR directly control the expression of the reb operon and that PraR dominantly represses reb expression. Furthermore, we found that the reb operon is highly expressed at low temperatures and that 2-oxoglutarate induces the expression of the reb operon by inhibiting PraR binding to the reb promoter. We conclude that R bodies are toxic not only in paramecium symbiosis but also in relationships between other bacteria and eukaryotic cells and that R-body formation is controlled by environmental factors. IMPORTANCE Caedibacter species, which are obligate endosymbiotic bacteria of paramecia, produce R bodies, and R-body-producing endosymbionts that are released from their hosts are pathogenic to symbiont-free paramecia. Besides Caedibacter species, R bodies have also been observed in a few free-living bacteria, but the significance of R-body production in these bacteria is still unknown. Recent advances in genome sequencing technologies revealed that many Gram-negative bacteria possess reb genes encoding R-body components, and interestingly, many of them are animal and plant pathogens. Azorhizobium caulinodans, a microsymbiont of the tropical legume Sesbania rostrata, also possesses reb genes. In this study, we demonstrate that A. caulinodans has ability to kill the host plant cells by producing R bodies, suggesting that pathogenicity conferred by an R body might be universal in bacteria possessing reb genes. Furthermore, we provide the first insight into the molecular mechanism underlying the expression of R-body production in response to environmental factors, such as temperature and 2-oxoglutarate.


Transcriptional profiling of arbuscular mycorrhizal roots exposed to high levels of phosphate reveals the repression of cell cycle-related genes and secreted protein genes in Rhizophagus irregularis
Mycorrhiza,27(2):139-146 2017(Feb.)
Author:Yusaku Sugimura; Katsuharu Saito
Abstract:The development of arbuscular mycorrhiza (AM) is strongly suppressed under high-phosphate (Pi) conditions. To investigate AM fungal responses during the suppression of AM by high Pi, we performed an RNA-seq analysis of Rhizophagus irregularis colonizing Lotus japonicus roots at different levels of Pi (20, 100, 300, and 500 mu M). AM fungal colonization decreased markedly under high-Pi conditions. In total, 163 fungal genes were differentially expressed among the four Pi treatments. Among these genes, a cell cycle-regulatory gene, cyclin-dependent kinase CDK1, and several DNA replication- and mitosis-related genes were repressed under high-Pi conditions. More than 20 genes encoding secreted proteins were also downregulated by high-Pi conditions, including the strigolactone-induced putative secreted protein 1 gene that enhances AM fungal colonization. In contrast, the expression of genes related to aerobic respiration and transport in R. irregularis were largely unaffected. Our data suggest that high Pi suppresses the expression of genes associated with fungal cell cycle progression or that encode secreted proteins that may be required for intercellular hyphal growth and arbuscule formation. However, high Pi has little effect on the transcriptional regulation of the primary metabolism or transport in preformed fungal structures.


Comparative transcriptome analysis between Solanum lycopersicum L. and Lotus japonicus L. during arbuscular mycorrhizal development
Soil Science and Plant Nutrition,63(2):127-136 2017
Author:Yusaku Sugimura; Katsuharu Saito
Abstract:Arbuscular mycorrhizal (AM) fungi form symbiotic associations with diverse plant species. The AM fungi enhance mineral uptake from the soil, which benefits the growth of the host plants. Previous microarray and RNA-seq analyses have identified a large number of AM-responsive plant genes. However, little is known whether the gene expression profile of mycorrhiza is different among genetically distant plant species. The aim of this study was to assess the conservation and divergence of AM-responsive genes between two different hosts, Solanum lycopersicum L. and Lotus japonicus L., during AM development using RNA-seq data. In each host plant, gene expression was compared between AM roots and non-mycorrhizal (NM) roots. Potential orthologs of AM-responsible genes between S. lycopersicum and L. japonicus were identified with reciprocal BLAST searches. Only one quarter to one third of the AM-inducible genes in each plant species were co-upregulated in both species. The co-upregulated genes included those known to be essential for AM development and function. The co-upregulated genes exhibited a wide range of fold changes in the AM symbiosis, and the fold change value for individual co-upregulated genes was positively correlated between the two hosts. Most of the species-dependent upregulated genes exhibited low levels of induction. We also analyzed gene expression in AM fungi colonizing roots of S. lycopersicum and L. japonicus. Overall, the gene expression profiles of Rhizophagus irregularis were similar among the roots of the two different hosts, although hundreds of fungal genes were differentially expressed between the two hosts. In particular, genes related to the mitochondrial electron transport chain were highly expressed in AM fungi colonizing L. japonicus roots, indicating that adenosine triphosphate (ATP) production was enhanced in the L. japonicus-R. irregularis symbiosis. Overall, these results show that a certain proportion of AM-responsive genes is conserved across plant species. The species-dependent AM-responsive genes may be related to the physiological differences between AM and NM roots in each plant species.


A putative TetR-type transcription factor AZC_3265 from the legume symbiont Azorhizobium caulinodans represses the production of R-bodies that are toxic to eukaryotic cells
Soil Science and Plant Nutrition,63(5):452-459 2017
Author:Jun-ichi Matsuoka; Fumiko Ishizuna; Keigo Kurumisawa; Kengo Morohashi; Tetsuhiro Ogawa; Makoto Hidaka; Katsuharu Saito; Tatsuhiro Ezawa; Toshihiro Aono
Abstract:Azorhizobium caulinodans ORS571 is a microsymbiont of the legume Sesbania rostrata, which forms nitrogen-fixing nodules on stems and roots. This bacterium harbors a reb operon, which is associated with R-body production. R-bodies are large proteinaceous ribbons and were first observed in Caedibacter species, which are obligate bacterial endosymbionts in paramecia. R-body-producing Caedibacter species released from their host paramecia are toxic to the symbiont-free paramecia. R-body-producing cells of A. caulinodans mutants are also toxic to the plant host cells. To maintain harmonic symbiosis with S. rostrata, A. caulinodans has to repress the expression of the reb operon. To date, it has been revealed that the PraR transcription factor and Lon protease repress reb operon expression, in direct and indirect manners, respectively. In this study, we carried out transposon-based mutagenesis screening, and found that the AZC_3265 (locus tag on the genome) gene encoding a putative TetR-type transcription factor was involved in the repression of reb operon expression. The AZC_3265 gene deletion mutant showed high levels of reb operon expression and R-body formation, and this strain formed stem nodules defective in nitrogen-fixing activity. Systematic evolution of ligands by exponential enrichment (SELEX) experiment revealed that AZC_3265 protein could bind to the consensus palindromic sequence TTGC-N6-GCAA. However, this consensus sequence was not found in the reb operon promoter region. Additionally, an electrophoretic mobility shift assay (EMSA) also revealed that AZC_3265 could not bind to the reb operon promoter region. These results suggested that AZC_3265 repressed the expression of the reb operon in an indirect manner. In conclusion, the present data demonstrated that multiple regulators participate in the regulation of expression of the reb operon. The presence of multiple mechanisms for regulating the expression of the reb operon suggested that its expression was controlled in response to multiple biological and environmental factors.


Aquaporin-mediated long-distance polyphosphate translocation directed towards the host in arbuscular mycorrhizal symbiosis: application of virus-induced gene silencing
New Phytologist,211(4):1202-1208 2016(Sep.)
Author:Yusuke Kikuchi; Nowaki Hijikata; Ryo Ohtomo; Yoshihiro Handa; Masayoshi Kawaguchi; Katsuharu Saito; Chikara Masuta; Tatsuhiro Ezawa
Abstract:Arbuscular mycorrhizal fungi translocate polyphosphate through hyphae over a long distance to deliver to the host. More than three decades ago, suppression of host transpiration was found to decelerate phosphate delivery of the fungal symbiont, leading us to hypothesize that transpiration provides a primary driving force for polyphosphate translocation, probably via creating hyphal water flow in which fungal aquaporin(s) may be involved. The impact of transpiration suppression on polyphosphate translocation through hyphae of Rhizophagus clarus was evaluated. An aquaporin gene expressed in intraradical mycelia was characterized and knocked down by virus-induced gene silencing to investigate the involvement of the gene in polyphosphate translocation.Rhizophagus clarus aquaporin 3 (RcAQP3) that was most highly expressed in intraradical mycelia encodes an aquaglyceroporin responsible for water transport across the plasma membrane. Knockdown of RcAQP3 as well as the suppression of host transpiration decelerated polyphosphate translocation in proportion to the levels of knockdown and suppression, respectively. These results provide the first insight into the mechanism underlying long-distance polyphosphate translocation in mycorrhizal associations at the molecular level, in which host transpiration and the fungal aquaporin play key roles. A hypothetical model of the translocation is proposed for further elucidation of the mechanism.


RNA-seq Transcriptional Profiling of an Arbuscular Mycorrhiza Provides Insights into Regulated and Coordinated Gene Expression in Lotus japonicus and Rhizophagus irregularis
Plant and Cell Physiology,56(8):1490-1511 2015(Aug.)
Author:Yoshihiro Handa; Hiroyo Nishide; Naoya Takeda; Yutaka Suzuki; Masayoshi Kawaguchi; Katsuharu Saito
Abstract:Gene expression during arbuscular mycorrhizal development is highly orchestrated in both plants and arbuscular mycorrhizal fungi. To elucidate the gene expression profiles of the symbiotic association, we performed a digital gene expression analysis of Lotus japonicus and Rhizophagus irregularis using a HiSeq 2000 next-generation sequencer with a Cufflinks assembly and de novo transcriptome assembly. There were 3,641 genes differentially expressed during arbuscular mycorrhizal development in L. japonicus, approximately 80% of which were up-regulated. The up-regulated genes included secreted proteins, transporters, proteins involved in lipid and amino acid metabolism, ribosomes and histones. We also detected many genes that were differentially expressed in small-secreted peptides and transcription factors, which may be involved in signal transduction or transcription regulation during symbiosis. Coregulated genes between arbuscular mycorrhizal and root nodule symbiosis were not particularly abundant, but transcripts encoding for membrane traffic-related proteins, transporters and iron transport-related proteins were found to be highly co-up-regulated. In transcripts of arbuscular mycorrhizal fungi, expansion of cytochrome P450 was observed, which may contribute to various metabolic pathways required to accommodate roots and soil. The comprehensive gene expression data of both plants and arbuscular mycorrhizal fungi provide a powerful platform for investigating the functional and molecular mechanisms underlying arbuscular mycorrhizal symbiosis.


Up-regulation of genes involved in N-acetylglucosamine uptake and metabolism suggests a recycling mode of chitin in intraradical mycelium of arbuscular mycorrhizal fungi
Mycorrhiza,25(5):411-417 2015(Jul.)
Author:Yoshihiro Kobae; Miki Kawachi; Katsuharu Saito; Yusuke Kikuchi; Tatsuhiro Ezawa; Masayoshi Maeshima; Shingo Hata; Toru Fujiwara
Abstract:Arbuscular mycorrhizal (AM) fungi colonize roots and form two kinds of mycelium, intraradical mycelium (IRM) and extraradical mycelium (ERM). Arbuscules are characteristic IRM structures that highly branch within host cells in order to mediate resource exchange between the symbionts. They are ephemeral structures and at the end of their life span, arbuscular branches collapse from the tip, fungal cytoplasm withdraws, and the whole arbuscule shrinks into fungal clumps. The exoskeleton of an arbuscule contains structured chitin, which is a polymer of N-acetylglucosamine (GlcNAc), whereas a collapsed arbuscule does not. The molecular mechanisms underlying the turnover of chitin in AM fungi remain unknown. Here, a GlcNAc transporter, RiNGT, was identified from the AM fungus Rhizophagus irregularis. Yeast mutants defective in endogenous GlcNAc uptake and expressing RiNGT took up C-14-GlcNAc, and the optimum uptake was at acidic pH values (pH 4.0-4.5). The transcript levels of RiNGT in IRM in mycorrhizal Lotus japonicus roots were over 1000 times higher than those in ERM. GlcNAc-6-phosphate deacetylase (DAC1) and glucosamine-6-phosphate isomerase (NAG1) genes, which are related to the GlcNAc catabolism pathway, were also induced in IRM. Altogether, data suggest the existence of an enhanced recycling mode of GlcNAc in IRM of AM fungi.


pH measurement of tubular vacuoles of an arbuscular mycorrhizal fungus, Gigaspora margarita
Mycorrhiza,25(1):55-60 2015(Jan.)
Author:Rintaro Funamoto; Katsuharu Saito; Hiroshi Oyaizu; Toshihiro Aono; Masanori Saito
Abstract:Arbuscular mycorrhizal fungi play an important role in phosphate supply to the host plants. The fungal hyphae contain tubular vacuoles where phosphate compounds such as polyphosphate are accumulated. Despite their importance for the phosphate storage, little is known about the physiological properties of the tubular vacuoles in arbuscular mycorrhizal fungi. As an indicator of the physiological state in vacuoles, we measured pH of tubular vacuoles in living hyphae of arbuscular mycorrhizal fungus Gigaspora margarita using ratio image analysis with pH-dependent fluorescent probe, 6-carboxyfluorescein. Fluorescent images of the fine tubular vacuoles were obtained using a laser scanning confocal microscope, which enabled calculation of vacuolar pH with high spatial resolution. The tubular vacuoles showed mean pH of 5.6 and a pH range of 5.1-6.3. These results suggest that the tubular vacuoles of arbuscular mycorrhizal fungi have a mildly acidic pH just like vacuoles of other fungal species including yeast and ectomycorrhizal fungi.


Polyphosphate accumulation is driven by transcriptome alterations that lead to near-synchronous and near-equivalent uptake of inorganic cations in an arbuscular mycorrhizal fungus
New Phytologist,204(3):638-649 2014(Nov. 01)
Author:Yusuke Kikuchi; Nowaki Hijikata; Kaede Yokoyama; Ryo Ohtomo; Yoshihiro Handa; Masayoshi Kawaguchi; Katsuharu Saito; Tatsuhiro Ezawa
Abstract:Arbuscular mycorrhizal (AM) fungi accumulate a massive amount of phosphate as polyphosphate to deliver to the host, but the underlying physiological and molecular mechanisms have yet to be elucidated. In the present study, the dynamics of cationic components during polyphosphate accumulation were investigated in conjunction with transcriptome analysis. Rhizophagus sp. HR1 was grown with Lotus japonicus under phosphorus-deficient conditions, and extraradical mycelia were harvested after phosphate application at prescribed intervals. Levels of polyphosphate, inorganic cations and amino acids were measured, and RNA-Seq was performed on the Illumina platform. Phosphate application triggered not only polyphosphate accumulation but also near-synchronous and near-equivalent uptake of Na+, K+, Ca2+ and Mg2+, whereas no distinct changes in the levels of amino acids were observed. During polyphosphate accumulation, the genes responsible for mineral uptake, phosphate and nitrogen metabolism and the maintenance of cellular homeostasis were up-regulated. The results suggest that inorganic cations play a major role in neutralizing the negative charge of polyphosphate, and these processes are achieved by the orchestrated regulation of gene expression. Our findings provide, for the first time, a global picture of the cellular response to increased phosphate availability, which is the initial process of nutrient delivery in the associations.


Isolation and Phenotypic Characterization of Lotus japonicus Mutants Specifically Defective in Arbuscular Mycorrhizal Formation
Plant and Cell Physiology,55(5):928-941 2014(May)
Author:Tomoko Kojima; Katsuharu Saito; Hirosuke Oba; Yuma Yoshida; Junya Terasawa; Yosuke Umehara; Norio Suganuma; Masayoshi Kawaguchi; Ryo Ohtomo
Abstract:Several symbiotic mutants of legume plants defective in nodulation have also been shown to be mutants related to arbuscular mycorrhizal (AM) symbiosis. The origin of the AM symbiosis can be traced back to the early land plants. It has therefore been postulated that the older system of AM symbiosis was partially incorporated into the newer system of legume-rhizobium symbiosis. To unravel the genetic basis of the establishment of AM symbiosis, we screened about 34,000 plants derived from ethyl methanesulfonate (EMS)-mutagenized Lotus japonicus seeds by microscopic observation. As a result, three lines (ME778, ME966 and ME2329) were isolated as AM-specific mutants that exhibit clear AM-defective phenotypes but form normal effective root nodules with rhizobial infection. In the ME2329 mutant, AM fungi spread their hyphae into the intercellular space of the cortex and formed trunk hyphae in the cortical cells, but the development of fine branches in the arbuscules was arrested. The ME2329 mutant carried a nonsense mutation in the STR-homolog gene, implying that the line may be an str mutant in L. japonicus. On the ME778 and ME966 mutant roots, the entry of AM fungal hyphae was blocked between two adjacent epidermal cells. Occasionally, hyphal colonization accompanied by arbuscules was observed in the two mutants. The genes responsible for the ME778 and ME966 mutants were independently located on chromosome 2. These results suggest that the ME778 and ME966 lines are symbiotic mutants involved in the early stage of AM formation in L. japonicus.


Transcriptomic profiles of nodule senescence in Lotus japonicus and Mesorhizobium loti symbiosis
Plant Biotechnology,31(4):345-349 2014
Author:Sirinapa Chungopast; Hideki Hirakawa; Shusei Sato; Yoshihiro Handa; Katsuharu Saito; Masayoshi Kawaguchi; Shigeyuki Tajima; Mika Nomura
Abstract:Nodule senescence is a complex developmental process during which essential nutrients are recycled. In order to understand the regulatory mechanism, transcript-profiling analysis during nodule senescence was performed in the Lotus japonicus-Mesorhizobium loti symbiosis. Microarray data showed significantly up-regulated expressions in 641 genes out of a total of 20,165 genes during nodule senescence, and down-regulated expressions were observed in 416 genes. These up-regulated genes during senescence were related to cell wall/membrane/envelope biogenesis and extracellular structures. Down-regulated genes were mainly responsible for defense mechanisms. We classified senescence up-regulated genes in two clusters. Genes in cluster 1 were induced at senescence specific stage and those in cluster 2 were induced from nitrogen fixation stage and expressed until nodule senescence. The genes in cluster 1 included typical marker for senescence like gene for heat shock protein. Four hundred sixteen down-regulated genes during nodule senescence were also classified in two clusters, cluster 3 and cluster 4. These genes corresponded to metabolisms for amino acid and plant hormones which are necessary for growth and cell division during nodule development and nitrogen fixation. These results provide the comprehensive data source for investigation of molecular mechanisms underlying nodule senescence in Lotus japonicus-Mesorhizobium loti symbiosis.


Genome of an arbuscular mycorrhizal fungus provides insight into the oldest plant symbiosis
Proceedings of the National Academy of Sciences of the United States of America,110(50):20117-20122 2013(Dec.)
Author:Emilie Tisserant; Mathilde Malbreil; Alan Kuo; Annegret Kohler; Aikaterini Symeonidi; Raffaella Balestrini; Philippe Charron; Nina Duensing; Nicolas Frei Dit Frey; Vivienne Gianinazzi-Pearson; Luz B. Gilbert; Yoshihiro Handa; Joshua R. Herr; Mohamed Hijri; Raman Koul; Masayoshi Kawaguchi; Franziska Krajinski; Peter J. Lammers; Frederic G. Masclauxm; Claude Murat; Emmanuelle Morin; Steve Ndikumana; Marco Pagni; Denis Petitpierre; Natalia Requena; Pawel Rosikiewicz; Rohan Riley; Katsuharu Saito; Helene San Clemente; Harris Shapiro; Diederik Van Tuinen; Guillaume Becard; Paola Bonfante; Uta Paszkowski; Yair Y. Shachar-Hill; Gerald A. Tuskan; Peter W. Young; Ian R. Sanders; Bernard Henrissat; Stefan A. Rensing; Igor V. Grigoriev; Nicolas Corradi; Christophe Roux; Francis Martin
Abstract:The mutualistic symbiosis involving Glomeromycota, a distinctive phylum of early diverging Fungi, is widely hypothesized to have promoted the evolution of land plants during the middle Paleozoic. These arbuscular mycorrhizal fungi (AMF) perform vital functions in the phosphorus cycle that are fundamental to sustainable crop plant productivity. The unusual biological features of AMF have long fascinated evolutionary biologists. The coenocytic hyphae host a community of hundreds of nuclei and reproduce clonally through large multinucleated spores. It has been suggested that the AMF maintain a stable assemblage of several different genomes during the life cycle, but this genomic organization has been questioned. Here we introduce the 153-Mb haploid genome of Rhizophagus irregularis and its repertoire of 28,232 genes. The observed low level of genome polymorphism (0.43 SNP per kb) is not consistent with the occurrence of multiple, highly diverged genomes. The expansion of mating-related genes suggests the existence of cryptic sex-related processes. A comparison of gene categories confirms that R. irregularis is close to the Mucoromycotina. The AMF obligate biotrophy is not explained by genome erosion or any related loss of metabolic complexity in central metabolism, but is marked by a lack of genes encoding plant cell wall-degrading enzymes and of genes involved in toxin and thiamine synthesis. A battery of mycorrhiza-induced secreted proteins is expressed in symbiotic tissues. The present comprehensive repertoire of R. irregularis genes provides a basis for future research on symbiosis-related mechanisms in Glomeromycota.


Inorganic polyphosphates are stored in spherites within the midgut of Anticarsia gemmatalis and play a role in copper detoxification
Journal of Insect Physiology,58(2):211-219 2012(Feb.)
Author:F. M. Gomes; D. B. Carvalho; A. C. Peron; K. Saito; K. Miranda; E. A. Machado
Abstract:Inorganic polyphosphates (PolyP) are widespread molecules that have been shown to play a role in metal detoxification and heavy-metal tolerance. In the present report, we investigated the functional role of spherites as PolyP-metal binding stores in epithelial cells of the midgut of Anticarsia gemmatalis, a lepidopteran pest of soybean. Polyp stores were detected by DAPI staining and indirect immunohistochemistry as vesicles distributed in columnar cells and around goblet cell cavities. These PolyP vesicles were identified as spherites by their elemental profile in cell lysates that were partially modulated by P- or V-ATPases. Polyp levels along the midgut were detected using a recombinant exopolyphosphatase assay. When copper was added in the diet of larva, copper detection in spherites by X-ray microanalysis correlated with an increase in the relative phosphorous X-ray signal and with an increase in PolyP levels in epithelia cell lysate. Transmission electron microscopy of chemically fixed or cryofixed and freeze substituted tissues confirmed a preferential localization of spherites around the goblet cell cavity. Taken together, these results suggest that spherites store high levels of PolyP that are modulated during metal uptake and detoxification. The similarity between PolyP granules and spherites herein described also suggest that Polyp is one of the main phosphorous source of spherites found in different biological models. This suggests physiological roles played by spherites in the midgut of arthropods and mechanisms involved in heavy metal resistance among different insect genera. (C) 2011 Elsevier Ltd. All rights reserved.


Acidocalcisomes as Calcium- and Polyphosphate-Storage Compartments during Embryogenesis of the Insect Rhodnius prolixus Stahl
PLoS One,6(11):e27276 2011(Nov.)
Author:Isabela Ramos; Fabio Gomes; Carolina M. Koeller; Katsuharu Saito; Norton Heise; Hatisaburo Masuda; Roberto Docampo; Wanderley de Souza; Ednildo A. Machado; Kildare Miranda
Abstract:Background: The yolk of insect eggs is a cellular domain specialized in the storage of reserve components for embryo development. The reserve macromolecules are stored in different organelles and their interactions with the embryo cells are mostly unknown. Acidocalcisomes are lysosome-related organelles characterized by their acidic nature, high electron density and large content of polyphosphate bound to several cations. In this work, we report the presence of acidocalcisome-like organelles in eggs of the insect vector Rhodnius prolixus. Methodology/Principal findings: Characterization of the elemental composition of electron-dense vesicles by electron probe X-ray microanalysis revealed a composition similar to that previously described for acidocalcisomes. Following subcellular fractionation experiments, fractions enriched in acidocalcisomes were obtained and characterized. Immunofluorescence showed that polyphosphate polymers and the vacuolar proton translocating pyrophosphatase (V-H(+)-PPase, considered as a marker for acidocalcisomes) are found in the same vesicles and that these organelles are mainly localized in the egg cortex. Polyphosphate quantification showed that acidocalcisomes contain a significant amount of polyphosphate detected at day-0 eggs. Elemental analyses of the egg fractions showed that 24.5 +/- 0.65% of the egg calcium are also stored in such organelles. During embryogenesis, incubation of acidocalcisomes with acridine orange showed that these organelles are acidified at day-3 (coinciding with the period of yolk mobilization) and polyphosphate quantification showed that the levels of polyphosphate tend to decrease during early embryogenesis, being approximately 30% lower at day-3 compared to day-0 eggs. Conclusions: We found that acidocalcisomes are present in the eggs and are the main storage compartments of polyphosphate and calcium in the egg yolk. As such components have been shown to be involved in a series of dynamic events that may control embryo growth, results reveal the potential involvement of a novel organelle in the storage and mobilization of inorganic elements to the embryo cells.


Requirement for Mesorhizobium loti ornithine transcarbamoylase for successful symbiosis with Lotus japonicus as revealed by an unexpected long-range genome deletion
Plant and Cell Physiology,49(3):301-313 2008(Mar.)
Author:Elina Mishima; Atsuko Hosokawa; Haruko Imaizumi-Anraku; Katsuharu Saito; Masayoshi Kawaguchi; Kazuhiko Saeki
Abstract:With the original aim of surveying the role of exopolysaccharide (EPS) in LotusMesorhizobium symbiosis, we carried out Tn5 mutagenesis of Mesorhizobium loti and obtained 32 mutants with defects in EPS biosynthesis. One of the mutants, HIA22, formed pseudonodules and failed to fix nitrogen with Lotus japonicus. However, complementation analysis unexpectedly revealed that the potential gene with the locus tag, mll2073, interrupted by Tn5 was responsible for neither normal EPS synthesis nor symbiosis. Further analysis uncovered that HIA22 had a genome deletion of approximately 20 kbp, resulting in the loss of two separate genes responsible for EPS biosynthesis and symbiosis. One gene with the locus tag, mll5669, was needed to synthesize normal EPS that fluoresced on medium containing Calcofluor and encoded a homolog of O-antigen acetyl transferase in Salmonella typhimurium. A specific mutant of mll5669, EMB-B58, successfully fixed nitrogen when infected onto L. japonicus. Another gene, mlr5647, was needed to establish fully functional nodules and encoded ornithine carbamoyl transferase [ArgF (EC 2.1.3.3)], which participates in arginine biosynthesis. A specific mutant of mlr5647, EMB-Y2, showed arginine auxotrophy and formed infection threads, but the nodules formed by this strain had few infected cells filled with bacteroids. These mutant phenotypes were complemented by supplementation of arginine or citrulline to bacterial or plant medium. EMB-Y2 represented a novel class of rhizobial arginine auxotrophs with symbiotic deficiency, and its phenotypes indicated that sufficient supply of citrulline or its derivative is essential for successful infection or for a stage in the infection process in LotusMesorhizobium symbiosis.


Ultrastructure of rapidly frozen and freeze-substituted germ tubes of an arbuscular mycorrhizal fungus and localization of polyphosphate
New Phytologist,178(1):189-200 2008
Author:Yukari Kuga; Katsuharu Saito; Keiichiro Nayuki; R. Larry Peterson; Masanori Saito
Abstract:In arbuscular mycorrhizas (AM), the supply of phosphorus from the fungi is one of the most important benefits to the host plant. Here we describe for the first time the ultrastructure and polyphosphate (poly P) distribution in rapidly frozen and freeze-substituted germ tubes of the AM fungus Gigaspora margarita. At the ultrastructural level, phosphorus distribution was analysed using energy-filtering transmission electron microscopy, and poly P was detected using an enzyme-affinity method. Semithin sections and live cells were also stained with 4',6-diamidino-2-phenylindole, which is not specific but fluoresces yellow when viewed under UV irradiation by binding with poly P. The cryotechnique method showed that extensive elongate ellipsoid vacuoles containing a uniform electron-opaque material occupied most of the cell volume. Combining the results of multiple methods revealed that poly P was localized in a dispersed form in vacuoles and in the outer fungal cell wall. These results show the significant potential of AM fungi for phosphorus storage based on its localization in the extensive complement of vacuoles in thick hyphae. The mechanism of translocation of poly P in tubular vacuoles, and the role of poly P in the cell wall, need to be elucidated.


NUCLEOPORIN85 is required for calcium spiking, fungal and bacterial symbioses, and seed production in Lotus japonicus
Plant Cell,19(2):610-624 2007(Feb.)
Author:Katsuharu Saito; Makoto Yoshikawa; Koji Yano; Hiroki Miwa; Hisaki Uchida; Erika Asamizu; Shusei Sato; Satoshi Tabata; Haruko Imaizumi-Anraku; Yosuke Umehara; Hiroshi Kouchi; Yoshikatsu Murooka; Krzysztof Szczyglowski; J. Allan Downie; Martin Parniske; Makoto Hayashi; Masayoshi Kawaguchi
Abstract:In Lotus japonicus, seven genetic loci have been identified thus far as components of a common symbiosis (Sym) pathway shared by rhizobia and arbuscular mycorrhizal fungi. We characterized the nup85 mutants (nup85-1, -2, and - 3) required for both symbioses and cloned the corresponding gene. When inoculated with Glomus intraradices, the hyphae managed to enter between epidermal cells, but they were unable to penetrate the cortical cell layer. The nup85-2 mutation conferred a weak and temperature-sensitive symbiotic phenotype, which resulted in low arbuscule formation at 22 degrees C but allowed significantly higher arbuscule formation in plant cortical cells at 18 degrees C. On the other hand, the nup85 mutants either did not form nodules or formed few nodules. When treated with Nod factor of Mesorhizobium loti, nup85 roots showed a high degree of root hair branching but failed to induce calcium spiking. In seedlings grown under uninoculated conditions supplied with nitrate, nup85 did not arrest plant growth but significantly reduced seed production. NUP85 encodes a putative nucleoporin with extensive similarity to vertebrate NUP85. Together with symbiotic nucleoporin NUP133, L. japonicus NUP85 might be part of a specific nuclear pore subcomplex that is crucial for fungal and rhizobial colonization and seed production.


Simultaneous in situ detection of alkaline phosphatase activity and polyphosphate in arbuscules within arbuscular mycorrhizal roots
Functional Plant Biology,34(9):803-810 2007
Author:Rintaro Funamoto; Katsuharu Saito; Hiroshi Oyaizu; Masanori Saito; Toshihiro Aono
Abstract:Inorganic phosphate (Pi) metabolism in arbuscules of arbuscular mycorrhizal (AM) fungi is not well understood, although recent research has revealed that host plants absorb Pi around arbuscules with mycorrhiza-specific transporters. Therefore, we analysed the localisation of polyphosphate (polyP) and alkaline phosphatase (ALP) activity in arbuscules, which could be indicators of Pi metabolism. We developed a dual-labelling method for polyP and ALP activity, i.e. first labelling with fluorescent probes 4',6-diamidino-2-phenyl-indole dihydrochloride (DAPI) and then labelling with enzyme-labelled fluorescence (ELF97). The dual-labelling method made it possible to observe polyP and ALP activity signals simultaneously in mycorrhizal roots. The dual-labelling method revealed that ALP activity was mainly observed in mature arbuscules where polyP was rarely observed. The expression of the AM fungal ALP gene was suppressed in the knockdown plants of an AM-inducible Pi-transporter, and there was much polyP in arbuscules that showed low ALP activity. These topological observations suggest that there may be some relationships between polyP metabolism and ALP activity in arbuscules, and that these are, in part, controlled by Pi uptake by plants via the AM-inducible Pi-transporter.


Vacuolar localization of phosphorus in hyphae of Phialocephala fortinii, a dark septate fungal root endophyte
Canadian Journal of Microbiology,52(7):643-650 2006(Jul.)
Author:Saito K., Y. Kuga-Uetake, M. Saito and R. L. Peterson.
Abstract:Phialocephala fortinii is a dark septate fungal endophyte that colonizes roots of many host species. Its effect on plant growth varies from being pathogenic to beneficial. The basic biology of this species has received little research, and thus the main objectives of this study were to determine cytological features of hyphae, including the nature of the vacuolar system, and whether polyphosphate was present in vacuoles. Both living hyphae and hyphae that had been rapidly frozen and freeze substituted before embedding were studied. A complex system of vacuoles, including a motile tubular vacuolar system, elongated vacuoles, and spherical vacuoles, was demonstrated in living hyphae by the fluorescent probe Oregon Green 488 carboxylic acid diacetate, using laser scanning confocal microscopy. The motile tubular vacuolar system was more prevalent at the hyphal tip than in more distal regions, whereas elongated vacuoles and spherical vacuoles were more abundant distal to the tip. All vacuoles contained polyphosphate as shown by labelling embedded samples with recombinant polyphosphate binding domain of Escherichia coli exopolyphosphatase, containing Xpress tag at the N-terminal end, followed by anti-Xpress antibody and a secondary antibody conjugated either to a fluorescent probe for laser scanning confocal microscopy or colloidal gold for transmission electron microscopy. The polyphosphate was dispersed in vacuoles. This was confirmed by staining embedded samples with 4',6-diamidino-2-phenylindole and viewing with UV light using epifluorescence microscopy. These cytological methods showed that the tubular vacuolar system had lower concentrations of polyphosphate than the spherical vacuoles. Lipid bodies were present around vacuoles.


Polyphosphate metabolism in an acidophilic alga Chlamydomonas acidophila KT-1 (Chlorophyta) under phosphate stress
Plant Science,170(2):307-313 2006(Feb.)
Author:K Nishikawa; H Machida; Y Yamakoshi; R Ohtomo; K Saito; M Saito; N Tominaga
Abstract:In order to study the polyphosphate (PolyP) metabolism in the acidophilic alga, the effect of rapid change of external phosphate concentration (so-called Pi stress condition) on the distribution of PolyP in Chlamyclomonas acidophila KT-1 was investigated by fluorescent microscopy, in vivo P-31 NMR spectroscopy, and enzymatic quantification. The PolyP granules inside of C acidophila KT-I cells were observed by microscopy with a fluorescent dye 4',6-diarnidino-2-phenylindole (DAPI). Cells transferred from phosphate (Pi) deficient to Pi rich conditions were contained a large amount of PolyP and an additional new PolyP stain was observed around the cell surface. In comparison to a neutrophilic alga Chlamydomonas reinhardtii C-9, the total amount of PolyP in C. acidophila KT-1 was 2.5 times smaller. The lower content of PolyP in C. acidophila KT-1 was supposed to be attributable to the specific properties of its cell membrane, which limited to incorporate phosphate from the environment. Nevertheless, the trend of degradation and re-synthesis of PolyP in C. acidophila KT-1 was similar to that of C reinhardtii C-9 under Pi stress conditions with absolute PolyP amount being affected by the total phosphate in the cells. (c) 2005 Elsevier Ireland Ltd. All rights reserved.


シロクローバとアーバスキュラー菌根菌の共生関係およびその群集構造に及ぼすリン酸施肥の影響
日本草地学会誌,51(4):333-340 2006(Jan.)
Author:佐藤航一・斎藤勝晴・菅原和夫
Abstract:日本草地学会誌


Genetics of symbiosis in Lotus japonicus: Recombinant inbred lines, comparative genetic maps, and map position of 35 symbiotic loci
Molecular Plant-Microbe Interactions,19(1):80-91 2006(Jan.)
Author:N Sandal; TR Petersen; J Murray; Y Umehara; B Karas; K Yano; H Kumagai; M Yoshikawa; K Saito; M Hayashi; Y Murakami; XW Wang; T Hakoyama; H Imaizumi-Anraku; S Sato; T Kato; WL Chen; MS Hossain; S Shibata; TL Wang; K Yokota; K Larsen; N Kanamori; E Madsen; S Radutoiu; LH Madsen; TG Radu; L Krusell; Y Ooki; M Banba; M Betti; N Rispail; L Skot; E Tuck; J Perry; S Yoshida; K Vickers; J Pike; L Mulder; M Charpentier; J Muller; R Ohtomo; T Kojima; S Ando; AJ Marquez; PM Gresshoff; K Harada; J Webb; S Hata; N Suganuma; H Kouchi; S Kawasaki; S Tabata; M Hayashi; M Parniske; K Szczyglowski; M Kawaguchi; J Stougaard
Abstract:Development of molecular tools for the analysis of the plant genetic contribution to rhizobial and mycorrhizal symbiosis has provided major advances in our understanding of plant-microbe interactions, and several key symbiotic genes have been identified and characterized. In order to increase the efficiency of genetic analysis in the model legume Lotus japonicus, we present here a selection of improved genetic tools. The two genetic linkage maps previously developed from an interspecific cross between L. japonicus Gifu and L filicaulis, and an intraspecific cross between the two ecotypes L. japonicus Gifu and L. japonicus MG-20, were aligned through a set of anchor markers. Regions of linkage groups, where genetic resolution is obtained preferentially using one or the other parental combination, are highlighted. Additional genetic resolution and stabilized mapping populations were obtained in recombinant inbred lines derived by a single seed descent from the two populations. For faster mapping of new loci, a selection of reliable markers spread over the chromosome arms provides a common framework for more efficient identification of new alleles and new symbiotic loci among uncharacterized mutant lines. Combining resources from the Lotus community, map positions of a large collection of symbiotic loci are provided together with alleles and closely linked molecular markers. Altogether, this establishes a common genetic resource for Lotus spp. A web-based version will enable this resource to be curated and updated regularly.


Direct labeling of polyphosphate at the ultrastructural level in Saccharomyces cerevisiae by using the affinity of the polyphosphate binding domain of Escherichia coli exopolyphosphatase
Applied and Environmental Microbiology,71(10):5692-5701 2005(Oct.)
Author:K Saito; R Ohtomo; Y Kuga-Uetake; T Aono; M Saito
Abstract:Inorganic polyphosphate (polyP) is a linear polymer of orthophosphate and has many biological functions in prokaryotic and eukaryotic organisms. To investigate polyP localization, we developed a novel technique using the affinity of the recombinant polyphosphate binding domain (PPBD) of Escherichia coli exopolyphosphatase to polyP. An epitope-tagged PPBD was expressed and purified from E. coli. Equilibrium binding assay of PPBD revealed its high affinity for long-chain polyP and its weak affinity for short-chain polyP and nucleic acids. To directly demonstrate polyP localization in Saccharomyces cerevisiae on resin sections prepared by rapid freezing and freeze- substitution, specimens were labeled with PPBD containing an epitope tag and then the epitope tag was detected by an indirect immunocytochemical method. A goat anti-mouse immunoglobulin G antibody conjugated with Alexa 488 for laser confocal microscopy or with colloidal gold for transmission electron microscopy was used. When the S. cerevisiae was cultured in yeast extract-peptone-dextrose medium (10 mM phosphate) for 10 h, polyP was distributed in a dispersed fashion in vacuoles in successfully cryofixed cells. A few polyP signals of the labeling were sometimes observed in cytosol around vacuoles with electron microscopy. Under our experimental conditions, polyP granules were not observed. Therefore, it remains unclear whether the method can detect the granule form. The method directly demonstrated the localization of polyP at the electron microscopic level for the first time and enabled the visualization of polyP localization with much higher specificity and resolution than with other conventional methods.


Lotus burttii takes a position of the third corner in the Lotus molecular genetics triangle
DNA Research,12(1):69-77 2005
Author:Masayoshi Kawaguchi; Andrea Pedrosa-Harand; Koji Yano; Makoto Hayashi; Yoshikatsu Murooka; Katsuharu Saito; Toshiyuki Nagata; Kiyoshi Namai; Hiroshi Nishida; Daisuke Shibata; Shusei Sato; Satoshi Tabata; Masaki Hayashi; Kyuya Harada; Niels Sandal; Jens Stougaard; Andreas Bachmair; William F. Grant
Abstract:In order to consolidate molecular genetic system in Lotus japonicus and to further access the biological diversity in Lotea, we introduce here Lotus burttii B-303 derived from West Pakistan as the third crossing partner of the Gifu ecotype (B-129-S9) for a genetic analysis. L. burttii is a relatively small and early flowering plant with non-shattering behavior. The general chromosome morphology is very similar to Gifu, and fluorescence in situ hybridization (FISH) analysis revealed that the short arm of chromosome 1 in L. burttii is comparable to that of Gifu, indicating that the translocation event involving chromosomes 1 and 2, which was observed in L. japonicus Miyakojima MG-20, is not present in L. burttii. In addition L. burttii has a higher level of DNA polymorphism compared to Gifu and MG-20 enabling design of codominant markers such as SSR, CAPS and dCAPS. Using an F2 population from a cross between Gifu and L. burttii, codominant makers that co-segregated at the translocation site could be expanded. In order to normalize the genetic background, L. burttii was inbred for nine generations and the germplasm L. burttii B-303-S9 was established.


アーバスキュラー菌根における物質代謝と輸送:4億年前に確立された共生システムへの温故知“最新”的アプローチ
日本土壌肥料科学雑誌,75(6):737-746 2004(Dec.)
Author:江沢辰広・斎藤勝晴・青野俊裕
Abstract:日本土壌肥料科学雑誌


Defoliation effects on the community structure of arbuscular mycorrhizal fungi based on 18S rDNA sequences
Mycorrhiza,14(6):363-373 2004(Dec.)
Author:K Saito; Y Suyama; S Sato; K Sugawara
Abstract:The effects of defoliation on arbuscular mycorrhizal (AM) associations in the field were investigated in terms of the community structure of AM fungi colonizing roots of grassland plants; the carbohydrate balance of the host plants was also determined. We focused on two plant species dominating Japanese native grasslands: the grazing-intolerant species Miscanthus sinensis and the grazing-tolerant species Zoysia japonica. Community structures of AM fungi were determined from 18S rRNA gene sequences. The dominant fungal group in both plant species was the Glomus clade, which was classified into several phylogenetic groups based on genetic distances and topology. In Miscanthus roots, the Glomus-Ab, Glomus-Ac, and Glomus-Ad groups were detected almost equally. In Zoysia roots, the Glomus-Ab group was dominant. Defoliation effects on the community structure of AM fungi differed between the plant species. In Miscanthus roots, the percentage of root length colonized (%RLC) by the Glomus-Ac and Glomus-Ad groups was significantly reduced by defoliation treatment. On the other hand, AM fungal group composition in Zoysia roots was unaffected by defoliation except on the last sampling date. Decreased %RLC by Glomus-Ac and Glomus-Ad coincided with decreased non-structural carbohydrate (NSC) levels in host plants; also, significant positive correlations were found between the %RLC and some NSC levels. On the other hand, the %RLC by Glomus-Ab in both plant species was unaffected by the NSC level. These results suggest that AM fungal groups have different carbohydrate requirements from host plants.


Acidic vesicles in living hyphae ofan arbuscular mycorrhizal fungus, Gigaspora margarita
Plant and Soil,261(1-2):231-237 2004(Apr.)
Author:Saito K., Y. Uetake and M. Saito
Abstract:Localization and movement of organelles in living hyphae of an arbuscular mycorrhizal fungus, Gigaspora margarita, were observed using a combination of fluorescent probes and laser-scanning confocal microscopy. Dense, evenly distributed acidic vesicles were visible in germ tubes and extraradical hyphae using DIC with the fluorescent acidotropic probe LysoTracker. These vesicles were distinct from both tubular vacuoles stained with DFFDA and lipid bodies stained with BODIPY 493/503 or Nile Red. Tubular vacuole bundles appeared to be influenced by the bidirectional cytoplasmic streaming of acidic vesicles and lipid bodies. Movement of the acidic vesicles occurred bidrectionally at different rates. The size and distribution of lipid bodies were variable. Based on our observations, the function of these organelles is discussed in relation to nutrient translocation in arbuscular mycorrhizas.


放牧利用オーチャードグラス(Dactylis glomerata L.)のアーバスキュラー菌根形成に及ぼす表面施肥の影響
日本草地学会誌,49(1):52-54 2003
Author:烏恩・斎藤勝晴・佐藤衆介・菅原和夫
Abstract:日本草地学会誌


野草および牧草放牧地における共通出現植物のアーバスキュラー菌根菌感染率と根圏土壌胞子数
日本草地学会誌,48(3):248-253 2002
Author:烏恩・斎藤勝晴・佐藤衆介・菅原和夫
Abstract:日本草地学会誌


Nested PCR amplification of arbuscular mycorrhizal fungal 18S rRNA genes from field-collected roots
Grassland Science,47(1):1-8 2001
Author:Saito K., A. Nishiwaki and K. Sugawara
Abstract:Grassland Science


DNA extraction from arbuscular mycorrhizal roots of Miscanthus sinensis Anderss. collected in the native grassland
Grassland Science,46(2):182-184 2000
Author:Saito K., A. Nishiwaki and K. Sugawara
Abstract:Grassland Science


講演・口頭発表等
純粋培養で増殖したアーバスキュラー菌根菌の脂質組成
日本土壌肥料学会(愛媛大学) 2023(Sep. 12)
Presenter:藤原優介; 小澤元輝; 齋藤勝晴


土づくりのためのアーバスキュラー菌根菌の培養・貯蔵技術
大学見本市 2023~イノベーション・ジャパン(東京ビックサイト) 2023(Aug. 24)
Presenter:齋藤勝晴


SDGs農業を促進する共生微生物の培養・貯蔵技術
JST新技術説明会 (オンライン) 2023(Aug. 03)
Presenter:齋藤勝晴


気候変動と農業の関係を考える
北海道静内農業高校セミナー(オンライン) 2023(Jul. 21)
Presenter:齋藤勝晴


脂肪酸と糖の添加によるアーバスキュラー菌根菌の培養化
日本草地学会 2023(Mar. 27)
Presenter:藤原優介・齋藤勝晴


気候変動と農業の関係を考える
八ヶ岳中央農業実践大学校 農林技術アカデミー第16回セミナー 2023(Feb. 18)
Presenter:齋藤勝晴


アーバスキュラー菌根菌の非共生的成長に対する不飽和脂肪酸の効果
菌根研究会 2022(Dec. 10)
Presenter:小澤元輝・齋藤勝晴


Sustainable P resource management - The use of arbuscular mycorrhizal symbiosis
"Innovation in Sustainable Agriculture for Our Future", The 5th International Summer Course Unpad 2022 2022(Nov. 16)
Presenter:Saito, K


アーバスキュラー菌根菌の非共生的成長に対するオレイン酸の効果
日本土壌肥料学会 2022(Sep. 15)
Presenter:小澤元輝・齋藤勝晴


アーバスキュラー菌根菌VTC4はポリリン酸の合成と分解を触媒する
植物微生物研究会 2022(Sep. 08)
Presenter:Nguyen Thi Cuc・江沢辰広・齋藤勝晴


Utilization of myristate and palmitate as carbon sources in arbuscular mycorrhizal fungi
11th International Conference on Mycorrhiza 2022(Aug. 04)
Presenter:Sugiura, Y; Akiyama, R; Tanaka, S; Yano, K; Kameoka, H; Marui, S; Saito, M; Kawaguchi, M; Akiyama, K; Saito, K


土壌と肥料の基礎
ワイン大学 2022(Jun. 18)
Presenter:齋藤勝晴


アーバスキュラー菌根菌VTC4タンパク質のポリリン酸合成・利用反応
菌根研究会 2021(Nov. 13)
Presenter:Nguyen Thi Cuc・江沢辰広・齋藤勝晴


Stimulation of asymbiotic sporulation in arbuscular mycorrhizal fungi by fatty acids
日本生化学会 2021(Nov.)
Presenter:Kameoka, H., Saito, K., Kawaguchi, M., Akiyama, K.


菌根共生で誘導されるパープル酸性ホスファターゼ遺伝子の網羅的探索
日本土壌肥料学会 2021(Sep. 14)
Presenter:大橋実佳・杉村悠作・江沢辰広・齋藤勝晴


アーバスキュラー菌根菌の純粋培養の可能性
日本土壌肥料学会 2021(Sep. 14)
Presenter:杉浦優太・秋山礼伊・田中幸子・矢野幸司・亀岡啓・丸井汐里・齋藤雅典・川口正代司・秋山康紀・齋藤勝晴


アーバスキュラー菌根菌における脂肪酸誘導胞子の低温貯蔵性
日本土壌肥料学会 2021(Sep. 14)
Presenter:猪野晃司・齋藤勝晴


The cytosolicglycerol-3-phosphate dehydrogenase GPDH3 is required for the mycorrhizal symbiosis in Lotus japonicus.
植物微生物研究会 2021(Sep.)
Presenter:Yeh, T, Sugimura, Y., Igarashi, T., Katou, S., Saito, K.


アーバスキュラー菌根菌におけるミリスチン酸の炭素源としての利用
植物微生物研究会 2021(Sep.)
Presenter:杉浦優太・秋山礼伊・田中幸子・矢野幸司・亀岡啓・丸井汐里・齋藤雅典・川口正代司・秋山康紀・齋藤勝晴


固定化培養法によるアーバスキュラー菌根菌に非共生的増殖
日本菌学会 2021(Aug. 27)
Presenter:秋山礼伊・杉浦優太・田中幸子・矢野幸司・亀岡啓・丸井汐里・齋藤雅典・川口正代司・秋山康紀・齋藤勝晴


アーバスキュラー菌根菌の非共生的成長に対するミリスチン酸の効果
日本土壌微生物学会 2021(Jun. 19)
Presenter:杉浦優太・秋山礼伊・田中幸子・矢野幸司・亀岡啓・丸井汐里・齋藤雅典・川口正代司・秋山康紀・齋藤勝晴


ストリゴラクトンとジャスモン酸メチルは非共生状態でアーバスキュラー菌根菌R. clarus HR1の増殖を促進する
日本植物生理学会 2021(Mar.)
Presenter:田中幸子・橋本佳世・小林裕樹・矢野幸司・前田太郎・亀岡啓・江沢辰広・齋藤勝晴・秋山康紀・川口正代司


アーバスキュラー菌根菌の脂肪酸の利用性
日本土壌肥料学会 2020(Sep. 08)
Presenter:杉浦優太・秋山礼伊・田中幸子・矢野幸司・亀岡啓・丸井汐里・齋藤雅典・川口正代司・秋山康紀・齋藤勝晴


アーバスキュラー菌根菌におけるミリスチン酸の炭素源としての利用
日本菌学会 2020(Jun. 19)
Presenter:杉浦優太・秋山礼伊・田中幸子・矢野幸司・亀岡啓・丸井汐里・齋藤雅典・川口正代司・秋山康紀・齋藤勝晴
Abstract:日本菌学会


アーバスキュラー菌根のリン酸輸送におけるポリリン酸代謝の役割
植物微生物研究会 2019(Sep. 19)
Presenter:150. Nguyen Thi Cuc・齋藤勝晴
Abstract:植物微生物研究会


ミヤコグサH+-ATPase変異体を用いた菌根経路におけるリン酸輸送の解析
日本土壌肥料学会 2019(Sep. 05)
Presenter:Nguyen Thi Cuc・齋藤勝晴
Abstract:日本土壌肥料学会


非共生時のアーバスキュラー菌根菌の成長に対する脂肪酸の効果
日本土壌肥料学会 2019(Sep. 05)
Presenter:秋山礼伊・杉浦優太・齋藤勝晴
Abstract:日本土壌肥料学会


Polyphosphate metabolism in arbuscular mycorrhizal fungi in relation to phosphate transfer to their host
10th International Conference on Mycorrhiza. Merida, Mexico. 2019(Jul. 02)
Presenter:Saito, K.
Abstract:10th International Conference on Mycorrhiza. Merida, Mexico.


Fatty acids promote energy production of arbuscular mycorrhizal fungi under asymbiotic conditions
10th International Conference on Mycorrhiza. Merida, Mexico. 2019(Jul. 01)
Presenter:Akiyama, R., Sugiura, Y., Saito, K.
Abstract:10th International Conference on Mycorrhiza. Merida, Mexico.


Fungal phosphate export via SYG1 triggers symbiosis-specific lipid biosynthesis in the host of arbuscular mycorrhiza
植物生理学会 2019(Mar. 13)
Presenter:Maruyama, H., Asaeda, S., Yokoyama, K., Sugimura, Y., Saito, K., Masuta, C., Ezawa, T.
Abstract:植物生理学会


Polyphosphate localization in Rhizophagus irregularis colonizing in a H+-ATPase ha1 mutant of Lotus japonicus
4th International Molecular Mycorrhiza Meeting 2019(Feb. 07)
Presenter:Nguyen, T. C., Saito, K.
Abstract:4th International Molecular Mycorrhiza Meeting


Glycerol-3 phosphate dehydrogenase GPDH3 is involved in arbuscule branching in Lotus japonicus
4th International Molecular Mycorrhiza Meeting 2019(Feb. 07)
Presenter:Igarashi, T., Sugimura, Y., Saito, K.
Abstract:4th International Molecular Mycorrhiza Meeting


菌根菌からのリン酸放出が樹枝状体形成に関わる植物遺伝子群の発現を調節する
菌根研究会 2018(Dec. 08)
Presenter:丸山隼人・浅枝諭史・横山 楓・杉村悠作・齋藤勝晴・増田 税・江沢辰広
Abstract:菌根研究会


樹枝状形成に関与する脂肪合成経路
植物微生物研究会 2018(Sep. 19)
Presenter:五十嵐大義・杉村悠作・齋藤勝晴
Abstract:植物微生物研究会


樹枝状体形成におけるグリセロール-3-リン酸デヒドロゲナーゼGPDH3の関与
日本土壌肥料学会 2018(Aug. 29)
Presenter:五十嵐大義・杉村悠作・齋藤勝晴
Abstract:日本土壌肥料学会


Glycerol-3 phosphate dehydrogenase GPDH3 is required for arbuscule formation in Lotus japonicus
The 23rd International Symposium on Plant Lipids 2018(Jul. 08)
Presenter:Igarashi, T., Sugimura, Y., Saito, K.
Abstract:The 23rd International Symposium on Plant Lipids


Arbuscular mycorrhizal communities in semi-natural grasslands
7th International Symposium on Integrated Field Science 2009
Presenter:Saito, K
Abstract:7th International Symposium on Integrated Field Science


MISC
書評「われら古細菌の末裔−微生物から見た生物の進化−」
日本土壌肥料科学雑誌,94(3):244 2023(Jun. 05)
Author:齋藤勝晴


Role of polyphosphate in arbuscular mycorrhizal fungi
IMS Newsletter,3(2) 2022(Jul.)
Author:Nguyen, T. C. and Saito, K.


純粋培養によるアーバスキュラー菌根菌の資材開発
作物生産と土つくり,54(569):1-5 2022(Jul.)
Author:齋藤勝晴


有用土壌微生物アーバスキュラー菌根菌の純粋培養法の確立
バイオサイエンスとインダストリー,78(1):8-13 2020(Jan.)
Author:亀岡啓・齋藤勝晴・川口正代司・秋山康紀
Abstract:バイオサイエンスとインダストリー


植生をめぐる微生物の生態学 ─ はじめに ─
日本草地学会誌,64(4):261-262 2019(Jan.)
Author:菅原幸哉・山下雅幸・齋藤勝晴
Abstract:日本草地学会誌


Toward assessing the contribution of arbuscular mycorrhizal symbiosis to plant P nutrition
Journal of Integrated Field Science,15:26-30 2018(Oct.)
Author:Saito, K.
Abstract:Journal of Integrated Field Science


はじめに(<特集>草地・耕地生態系の菌根の生理生態と利用)
日本草地学会誌,59(4):261-262 2014
Author:齋藤勝晴
Abstract:日本草地学会誌


菌根共生からみる植物栄養の新時代
日本土壌肥料学雑誌,85(3):279-284 2014
Author:小八重善裕・東樹宏和・山本哲史・竹本大吾・江沢辰広・河原愛・荒川竜太・齋藤勝晴・中川知己
Abstract:日本土壌肥料学雑誌


アーバスキュラー菌根菌:研究の最前線と土壌肥料分野への貢献
日本土壌肥料学雑誌,83(2):216-221 2012(Apr.)
Author:坂本一憲・秋山康紀・林英雄・磯部勝孝・江澤辰広・菊池裕介・土方野分・俵谷圭太郎・伊豆進・齋藤勝晴
Abstract:日本土壌肥料学雑誌


アーバスキュラー菌根菌との共生
細胞工学,30(2):149-154 2011
Author:齋藤勝晴・林誠
Abstract:細胞工学


Seasonal variation of arbuscular mycorrhizal fungal colonization for coexisting plant species in Miscanthus-type semi-natural grassland
Journal of Integrated Field Science,7:29-35 2010
Author:Saito K. and K. Sugawara
Abstract:Journal of Integrated Field Science


共生 : その2 菌根菌(第3部門 土壌生物)
日本土壌肥料学雑誌,79(6):555-557 2008
Author:齋藤勝晴
Abstract:日本土壌肥料学雑誌


アーバスキュラー菌根実験法(7)アーバスキュラー菌根菌の生体観察法
土と微生物,61(1):79-82 2007(Apr.)
Author:斎藤勝晴・久我ゆかり・斎藤雅典
Abstract:土と微生物


アーバスキュラー菌根実験法(4)アーバスキュラー菌根菌の分離・増殖・接種法
土と微生物,60(1):71-73 2006(Apr.)
Author:斎藤勝晴・田島賢
Abstract:土と微生物


アーバスキュラー菌根実験法(2)アーバスキュラー菌根の観察
土と微生物,60(1):57-61 2006(Apr.)
Author:大場広輔・斎藤勝晴・藤吉正明
Abstract:土と微生物


Arbuscular菌根研究へのDNAマーカーの応用
東北草地研究会誌,11(6):49-56 1998
Author:斎藤勝晴・菅原和夫
Abstract:東北草地研究会誌

特許等知的財産
登録済特許
菌根菌の培養培地
共同研究等希望テーマ
アーバスキュラー菌根共生の分子生物学、細胞生物学、分子生態学および植物生産への応用
提供可能な資源
大腸菌エクソポリホスファターゼのポリリン酸結合ドメイン(His tag, Xpress tag)(Applied and Environmental Microbiology. 2005. 71(10), 5692-5701.)
研究費
科学研究費補助金(研究代表者)
2022 - 2024 , アーバスキュラー菌根菌の培養技術の高度化 , 基盤研究(B)
2019 - 2021 , アーバスキュラー菌根の脂質代謝・輸送・制御に関わる分子メカニズム , 基盤研究(B)
2011 - 2013 , アーバスキュラー菌根のリン酸輸送メカニズムの解明 , 若手研究(B)
2008 - 2010 , 共生変異体を用いたマメ科植物の共生的リン酸獲得機構の解析 , 若手研究(A)
2008 - 2010 , 菌根共生系の窒素代謝機構とその土壌圏の窒素循環における意義 , 基盤研究(B)
2007 - 2008 , 菌根における共生的リン酸獲得の分子機構 , 若手研究(スタートアップ)

科学研究費補助金(研究分担者)
2016 - 2019 , セスバニア根粒菌が巨大構造体R-bodyにより宿主細胞核を崩壊させる分子機構 , 基盤研究(C)
2015 - 2019 , 地域資源としてのきのこを高度・多面的に活用した新たな社会モデルの構築 , 基盤研究(A)
2014 - 2016 , 植物絶対共生菌の革新的遺伝子サイレンシング法が開く菌根共生の分子基盤 , 基盤研究(B)
2010 - 2014 , アーバスキュラー菌根共生系から根粒共生系への進化基盤の解明 , 新学術領域研究(研究領域提案型)
2009 - 2012 , 植物-微生物共生を支える普遍的宿主因子の解明 , 基盤研究(B)

その他公的資金
2009 - , ダイズのハイブリッド品種育種に向けた温度感応性雄性不稔植物の開発
2014 - 2019 , 共生ネットワークの分子基盤とその応用展開
2012 - 2013 , 農作物の放射性セシウム吸収抑制技術の開発
2002 - 2007 , 共生ネットワークの分子基盤

その他
2012 - 2014 , リン資源の循環的利用に向けた菌根共生機能の評価技術の開発
研究諸活動
学術専門雑誌等編集
2023- , Soil Science and Plant Nutrition
2022- , Frontiers in Plant Science
2022- , Microbes and Environments
2022- , 日本草地学会誌
2015- , Grassland Science

教育活動実績

授業等
2021 , 前期 , 植物生理学(分担)
2021 , 前期 , 植物資源科学基礎実験(分担)
2021 , 前期 , 科学英語I
2021 , 前期 , 新入生ゼミナール
2021 , 前期 , キャリア農学演習
2021 , 前期 , 先端生命科学特論
2021 , 前期 , 生物共生科学特別演習I
2021 , 後期 , 土壌学
2021 , 後期 , 植物栄養学
2021 , 後期 , 農環境保全学(分担)
2021 , 後期 , 植物資源科学実験I(分担)
2021 , 後期 , プレゼンテーション演習
2021 , 後期 , 農環境特論
2021 , 後期 , 生物共生科学特別演習II
2021 , 通年 , 科学英語II
2021 , 通年 , 専攻演習
2021 , 通年 , 専攻研究
2021 , 通年 , 生物共生科学特別実験実習
2021 , 通年 , 特別研究
2021 , 通年 , 土壌生物学特論