GRAIN INCOMPLETE FILLING 2 regulates grain filling and starch synthesis during rice caryopsis development. Issue 2 (February 2017)

• Record Type: Journal Article
• Authors: Wei, Xiangjin; Jiao, Guiai; Lin, Haiyan; Sheng, Zhonghua; Shao, Gaoneng; Xie, Lihong; Tang, Shaoqing; Xu, Qingguo; Hu, Peisong
• Is Part Of: Journal of integrative plant biology. Volume 59:Issue 2(2017)
• Page Start: 134
• Page End: 153
• Publication Date: 2017-02
• Subjects: Plants -- Periodicals; Plants -- China -- Periodicals; Electronic journals; 580.5
• DOI: 10.1111/jipb.12510
• Languages: English
• ISSNs: 1672-9072

Abstract

Abstract: Rice grain filling determines grain weight, final yield and grain quality. Here, a rice defective grain filling mutant, gif2, was identified. Grains of gif2 showed a slower filling rate and a significant lower final grain weight and yield compared to wild‐type. The starch content in gif2 was noticeably decreased and its physicochemical properties were also altered. Moreover, gif2 endosperm cells showed obvious defects in compound granule formation. Positional cloning identified GIF2 to encode an ADP‐glucose pyrophosphorylase (AGP) large subunit, AGPL2; consequently, AGP enzyme activity in gif2 endosperms was remarkably decreased. GIF2 is mainly expressed in developing grains and the coded protein localizes in the cytosol. Yeast two hybrid assay showed that GIF2 interacted with AGP small subunits OsAGPS1, OsAGPS2a and OsAGPS2b. Transcript levels for granule‐bound starch synthase, starch synthase, starch branching enzyme and starch debranching enzyme were distinctly elevated in gif2 grains. In addition, the level of nucleotide diversity of the GIF2 locus was extremely low in both cultivated and wild rice. All of these results suggest that GIF2 plays important roles in the regulation of grain filling and starch biosynthesis during caryopsis development, and that it has been preserved during selection throughout domestication of modern rice. Abstract : A rice mutant, gif2, displays remarkable slower grain filling rate, obvious defects in endosperm compound starch granule formation and less grain weight. Our work suggests that GIF2 encodes a large subunit of ADP‐glucose pyrophosphorylase and plays a key role in the regulation of grain filling and endosperm starch biosynthesis.