The Effect of Loss of TGW6 on Starch Accumulation and Toranslocation in Rice

• Project/Area Number: 16K14840
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Crop production science
• Research Institution: Toyo University
• Principal Investigator: Hirotsu Naoki 東洋大学, 生命科学部, 教授 (40584389)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000); Fiscal Year 2018: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000); Fiscal Year 2017: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000); Fiscal Year 2016: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
• Keywords: イネ / オーキシン / デンプン蓄積 / 登熟 / デンプン / ソース能 / 代謝 / 炭水化物蓄積 / インドール酢酸

Outline of Final Research Achievements

NIL(TGW6), near-isogenic line carrying Kasalath type (loss of function) chromosome around TGW6 gene in Koshihikari background were used in this study. NIL(TGW6) accumulated starch in lower leaf sheath compared with Koshihikari. The expression level of genes related starch synthesis were up-regulated and starch degradation were down-regulated in NIL(TGW6). Similarly, IAA inhibitor treated Koshihikari significantly increased starch contents in lower leaf sheath, and showed similar gene expression as NIL(TGW6). It is considered that IAA involves in starch degradation in the lower leaf sheath of rice. By field trial, NIL(TGW6) significantly increased perfect grain ratio than Koshihikari. The starch accumulated in NIL(TGW6) by the heading stage was translocated to panicle via culm by the Maturity stage. It is suggested that the higher supply capacity of carbohydrate could be kept demand of carbohydrates during the ripening stage and reduced the immature grains.

Academic Significance and Societal Importance of the Research Achievements

これまでにIAAとデンプン代謝の明確な関わりは報告されておらず、本研究を起点としてこれらの関係が明らかにされていくものと期待される。また、NIL(TGW6)はデンプン蓄積によるソース能の向上により、基部未熟粒などの未熟粒の発生を抑えて整粒割合を増加させる特性をもつことが示唆されたため、例えば高温登熟障害などの改善に機能喪失型TGW6が応用されうるのではないかと期待される。

Research Products

• [Journal Article] Partial loss-of-function of NAL1 alters canopy photosynthesis by changing the contribution of upper and lower canopy leaves in rice. (2018)
  • Author(s): Naoki Hirotsu, Kazuhiro Ujiie, Ishara Perera, Ayano Iri, Takayuki Kashiwagi & Ken Ishimaru.
  • Journal Title: Scientific Reports Volume: 7 Issue: 1 Pages: 15958-15958
  • DOI: 10.1038/s41598-017-15886-5
  • Peer Reviewed / Open Access
• [Presentation] Effect of loss of TGW6 on starch translocation and grain filling (2018)
  • Author(s): Noguchi M, Shimizu J, Sugisaki F, Ishimaru K, Hirotsu N.
  • Organizer: 5th International Rice Congress
  • Int'l Joint Research
• [Presentation] The Effect of IAA Inhibitor on Starch Accumulation in Rice Leaves (2018)
  • Author(s): Kawawa S, Ishimaru K, Hirotsu N.
  • Organizer: 5th International Rice Congress
  • Int'l Joint Research
• [Presentation] 機能喪失型TGW6によるデンプン転流の変化と登熟障害耐性への影響 (2018)
  • Author(s): 野口雅弘、清水順平、杉崎文哉、石丸健、廣津直樹
  • Organizer: 第245回日本作物学会講演会
• [Presentation] 機能喪失型TGW6における葉へのデンプン蓄積メカニズムの解析 (2017)
  • Author(s): 川和 信一郎, 石丸 健, 廣津 直樹
  • Organizer: 第244回日本作物学会講演会