Characterization of iron-reducing and iron-oxidizing microorganisms in rice rhizosphere under iron-toxic conditions in inland valley paddy fields of West Africa

2022 Fiscal Year Final Research Report

• Project/Area Number: 17H04619
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 海外学術
• Research Field: Plant nutrition/Soil science
• Research Institution: Nagoya University
• Principal Investigator: ASAKAWA Susumu 名古屋大学, 生命農学研究科, 教授 (50335014)
• Co-Investigator(Kenkyū-buntansha): 渡邉 健史 名古屋大学, 生命農学研究科, 講師 (60547016)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Keywords: 土壌学

Outline of Final Research Achievements

Iron toxicity in rice caused by higher contents of ferrous iron generated under anoxic conditions brings about severe deterioration of paddy rice production in some areas of the tropics. This research project focused on the microorganisms involved in the redox cycle of iron in the rhizosphere of rice under iron toxic conditions. Microbial community structures of iron reducers and oxidizers were investigated in the bulk and rhizosphere soil and root samples of rice plants with and without the symptoms of iron toxicity in an iron-toxic paddy field in the Kou valley, Burkina Faso, West Africa. The characteristics of the communities of iron reducers and oxidizers were compared with those in a paddy field in Japan without iron toxicity. Irrespective of the symptoms of iron toxicity in rice, a clear predominance of iron reducers over iron oxidizers was revealed in the rice rhizosphere in the iron-toxic paddy field, which corresponded well to the higher contents of ferrous iron in the soil.

Free Research Field

土壌微生物学

Academic Significance and Societal Importance of the Research Achievements

実際にイネの収量低下の大きな被害が発生している西アフリカの内陸盆地の鉄過剰水田を対象に、水稲根圏の鉄還元・酸化微生物群集を調査・解析し、二価鉄を酸化し過剰害軽減への寄与が期待される鉄酸化菌よりも、過剰害の主要因である二価鉄を生成する鉄還元菌が優占していることを初めて明らかにした。この知見は、鉄過剰水田において鉄代謝関連微生物の活性を制御・利活用し、イネの鉄過剰被害を軽減する方策を考える上で極めて重要かつ有用と考えられる。