Elucidating the control mechanisms of starch struture through the analyses of starch structure and protein interaction using starch branching enzyme deficient mutant rice lines.

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K14438
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 38060:Applied molecular and cellular biology-related
• Research Institution: Akita Prefectural University
• Principal Investigator: CROFTS Naoko 秋田県立大学, 生物資源科学部, 研究員 (30583330)
• Project Period (FY): 2018-04-01 – 2020-03-31
• Keywords: イネ / 澱粉 / 枝作り酵素 / アミロース / 難消化性澱粉

Outline of Final Research Achievements

To understand the control mechanisms of starch structure, the roles of starch branching enzymes were revealed by analyzing the rice mutant lines in which two out of three starch branching isozymes were omitted.
be1/be2b mutant rice had opaque seeds with high amylose (52 %) and high resistant starch content (175 folds of WT). be1/be2a mutant rice had translucent seeds and its starch properties were similar to the be1 single mutant rice or WT rice. While, be2a/be2b mutant were essentially sterile. These results suggests that the rile of each BE isozyme is partly specific, but can be compensated by other isozymes to some degree.

Free Research Field

澱粉性合成

Academic Significance and Societal Importance of the Research Achievements

澱粉の枝作り酵素（Branching enzyme; BE)は3種類あり、そのバランスが澱粉特性や米の用途を左右する。BEの相補関係を明確にするため、本研究では、二つの BEを同時に欠損させることで、残り一つとなったBEの役割を明確にした。be1/be2bの種子は白濁し、超高アミロース（約52％）で、難消化性澱粉含量が非常に高かった（WTの175倍）。BEIIaが存在することで、コメの収量を維持しつつ、腸内環境の改善や血糖値の急激な上昇を抑制する難消化性澱粉の含量を増やすことができることが明らかになった。