GRAIN INCOMPLETE FILLING 2 regulates grain filling and starch synthesis during rice caryopsis development
GRAIN INCOMPLETE FILLING 2 regulates grain filling and starch synthesis during rice caryopsis development
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谷物不完全灌浆 2 调节水稻颖果发育过程中的籽粒灌浆和淀粉合成
DOI：
10.1111/jipb.12510
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发表时间：
2017-02-01
影响因子：
11.4
通讯作者：
Hu, Peisong
中科院分区：
文献类型：
--
作者：
Wei, Xiangjin;Jiao, Guiai;Hu, Peisong
水稻籽粒灌浆决定粒重、最终产量和籽粒品质。本研究鉴定了一个水稻灌浆缺陷突变体gif 2。与野生型相比，gif 2的籽粒表现出较慢的灌浆速率和显著较低的最终粒重和产量。gif 2的淀粉含量明显降低，其理化性质也发生了变化。gif 2胚乳细胞在复合颗粒形成方面表现出明显的缺陷。定位克隆鉴定GIF 2编码ADP-葡萄糖焦磷酸化酶（AGP）大亚基，AGPL 2，因此，AGP酶活性在gif 2胚乳显着下降。GIF 2主要在发育中的籽粒中表达，其编码蛋白定位于胞质中。酵母双杂交实验表明GIF 2与AGP小亚基OsAGPS 1、OsAGPS 2a和OsAGPS 2b相互作用。gif 2籽粒中颗粒结合淀粉合成酶、淀粉合成酶、淀粉分支酶和淀粉去分支酶的转录水平明显升高。此外，在栽培稻和野生稻中，GIF 2基因座的核苷酸多样性水平极低。所有这些结果表明，GIF 2在颖果发育过程中的籽粒灌浆和淀粉合成的调节中起着重要作用，并且在现代水稻的驯化过程中，它一直被保留在选择过程中。
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.