2022 Fiscal Year Final Research Report

Identification of the mutant genes resistant to bacterial blight in rice, and elucidation of their resistance mechanisms

Research Project

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Project/Area Number	19H02934
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Review Section	Basic Section 39010:Science in plant genetics and breeding-related
Research Institution	Kagoshima University
Principal Investigator	Ichitani Katsuyuki 鹿児島大学, 農水産獣医学域農学系, 教授 (10305162)
Co-Investigator(Kenkyū-buntansha)	内海俊樹鹿児島大学, 理工学域理学系, 教授 (20193881) 岡本繁久鹿児島大学, 農水産獣医学域農学系, 准教授 (30211808) 清水圭一鹿児島大学, 農水産獣医学域農学系, 准教授 (30305164) 志水勝好鹿児島大学, 農水産獣医学域農学系, 教授 (40261771) 鈴木章弘佐賀大学, 農学部, 教授 (50305108) 村中智明名古屋大学, 大学院生命農学研究科, 助教 (50761938) 穴井豊昭九州大学, 農学研究院, 教授 (70261774) 田浦悟鹿児島大学, 総合科学域共同学系, 教授 (80216598)
Project Period (FY)	2019-04-01 – 2023-03-31
Keywords	抵抗性遺伝子
Outline of Final Research Achievements	We have reported three mutant Xanthomonas oryzae pv. oryze (Xoo) resistant lines, XM5, XM6 and XM14, derived from IR24, an indica rice cultivar (Taura et al. 1991a, Busungu et al. 2016). Although IR24 is susceptible to almost all Xoo strains, the three XM lines are resistant to all Xoo races tested (Taura et al. 1992, Busungu et al. 2016, Msami et al. 2021). XM5, XM6 and XM14 carries one pair of respective mutant recessive genes, xa19, xa20 and xa42. Using the combination of high-resolution linkage analysis and use of next generation DNA sequencer, we identified the causal DNA sequences making xa19, xa20 and xa42 resistant to Xoo. We also developed the new breeding material carrying these resistance genes. The physiology of the Xoo resistance conferred by xa42 was elucidated. Our findings suggest the possibility of creation of new resistance genes by slight mutation caused by a chemical mutagen MNU.
Free Research Field	植物育種学
Academic Significance and Societal Importance of the Research Achievements	私たちが同定した人為突然変異系統に由来するイネ白葉枯病抵抗性遺伝子はいずれも1塩基置換によるもので，２つはアミノ酸の非同義置換，１つはスプライシングの効率低下によると思われるものであった．また，2遺伝子は既知の抵抗性遺伝子とは異なる機能を持っていた．このことは，一般に塩基置換を誘発する化学変異原MNUの「軽度の」変異がもたらす新規突然変異抵抗性遺伝子開発の可能性を示唆している．