.ALPHA.-Amylase Affects Starch Accumulation in Rice Grains

DOI Web Site 19 Citations 28 References
  • Asatsuma Satoru
    Laboratories of Plant and Microbial Genome Control, Graduate School of Science and Technology, Niigata University
  • Sawada Chihoko
    Laboratories of Plant and Microbial Genome Control, Graduate School of Science and Technology, Niigata University
  • Kitajima Aya
    Laboratories of Plant and Microbial Genome Control, Graduate School of Science and Technology, Niigata University
  • Asakura Tsuyoshi
    Laboratories of Plant and Microbial Genome Control, Graduate School of Science and Technology, Niigata University
  • Mitsui Toshiaki
    Laboratories of Plant and Microbial Genome Control, Graduate School of Science and Technology, Niigata University Department of Applied Biological Chemistry, Niigata University

Bibliographic Information

Other Title
  • α-アミラーゼはイネ穀粒におけるデンプン蓄積に影響を及ぼす
  • α-Amylase affects starch accumulation in rice grains.
  • α-Amylase affects starch accumulation in the rice grain.

Abstract

α-Amylase isoforms I-1 and II-4 were found in rice grains during ripening, α-amylase II-4 being the most predominant isoform. To determine their functions in ripening seeds, we generated a series of transgenic rice plants transformed with α-amylase I-1 and α-amylase II-4 cDNA under the control of Cauliflower mosaic virus 35S promoter. These isoforms were increased in young shoot and mature leaf tissues of the transgenic plants at both mRNA and protein levels. The starch accumulation in leaves was reduced to 42-82% of that in the wild-type. The transgenic lines A3-1 and D1-4, which overexpressed α-amylase I-1 and α-amylase II-4, respectively, were examined further. The enzyme activity was increased in both seeds, and the increase was greater in D1-4. The dry weight of A3-1 and D1-4 seeds was decreased approximately 4 and 11%, respectively. White immature grains frequently appeared in both lines, with severer abnormalities seen in D1-4. These results strongly suggest that the increase of α-amylase activities inhibits the accumulation of reserve starch and lowers the grain quality of rice.

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