Analysis of starch biosynthesis with a novel rice dull mutant

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K05989
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 39020:Crop production science-related
• Research Institution: Hirosaki University
• Principal Investigator: Hnamada Shigeki 弘前大学, 農学生命科学部, 准教授 (90418608)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: イネ / デンプン / 低アミロース / 突然変異

Outline of Final Research Achievements

A new dull grain rice mutant with low amylose content, designated lowac1, has been isolated and characterized. Genotypes using the CAPS marker of the identified LowAC1 gene encoding an RNA recognition motif (RRM) protein were entirely consistent with low amylose phenotypes in BC1F2 progeny. lowac1 involves a single-nucleotide polymorphism from G to A within the gene, resulting in the stop codon generation. The RRM protein deletion in the mutant seed specifically affected the splicing efficiency of Waxyb (Wxb) in the 5′ splice site of intron 1, resulting in decreased protein levels of granule-bound starch synthase I (GBSSI) encoded by Wxb. Also, the mutation induced a little variation in the expression levels of some genes involved in starch biosynthesis. Aside from low amylose content, lowac1 seeds included an amylopectin structure reducing short chains compared to that of WT seeds. Overall, our data suggest that LowAC1 is a novel regulatory factor for starch synthesis in rice.

Free Research Field

植物生化学　酵素化学

Academic Significance and Societal Importance of the Research Achievements

食料自給率向上や安定的な食料生産の観点から、米の新規用途開発のために多様な形質をもった品種開発が望まれる。米の胚乳デンプンのアミロース含量は、炊飯米の食味の良否はもちろんのこと、米加工食品の加工適性においても重要な形質であることから、新たな付加価値が期待される低アミロース選抜系統について、原因遺伝子の同定および形質発現の機序を解明した。得られた成果は、デンプン生合成メカニズムの解明と新規形質米育成の基盤となる。さらには、加工適性や利用方法が見出されれば、米の新たな需要が開拓され農業や食品業界の活性化にも繋がり、次世代の食の多様性をもたらす農資源の開発に大きく貢献する。