Physiological mechanisms of carbohydrate utilization by N fixing endophyte for improving N fixation capacity in rice

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H02941
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 39020:Crop production science-related
• Research Institution: Nagoya University
• Principal Investigator: Kondo Motohiko 名古屋大学, 生命農学研究科, 教授 (00355538)
• Co-Investigator(Kenkyū-buntansha): 杉浦 大輔 名古屋大学, 生命農学研究科, 講師 (50713913)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: イネ / 窒素固定 / エンドファイト / 炭水化物 / 品種

Outline of Final Research Achievements

We analyzed the physiological and genetic factors related to the variation and improvement of nitrogen-fixing activity by nitrogen-fixing endophytes in rice plants. We found that stem nitrogen fixation activity is affected by the accumulation of NSCs, especially free sugars, and that activity is high in African rice CG14 and other rice cultivars. The involvement of sugars was also verified by analyzing starch synthesis mutant lines and by using shading. Furthermore, we analyzed the flora in the stem of rice cultivars with different nitrogen-fixing ability, and found that α- and β-proteobacteria were the main nitrogen-fixing bacteria. The results of the evaluation of the effect of nitrogen fertilization on the nitrogen fixation capacity in the field showed that the contribution to the total nitrogen absorption was relatively small, but nitrogen fertilization did not have a clear effect on the cumulative nitrogen fixation capacity.

Free Research Field

作物栄養

Academic Significance and Societal Importance of the Research Achievements

これまでほとんど知見のなかったイネ地上部のエンドファイト窒素固定の変動要因や関与する窒素固定菌叢の一端を示すことができた。活性の品種差異の要因のひとつが窒素固定に必要なエネルギーを供給する基質である可能性は、今後の活性の遺伝的向上のひとつの方向を示すものと考えている。イネは世界において主要作物であり、窒素化学肥料の削減を実現できればそのインパクトは大きいと考える。現状ではエンドファイトの寄与は非常に小さいが、今後土壌および体内エンドファイトを統合的に向上させる要因をさらに解明することが有効であると考える。