LARGE GRAIN Encodes a Putative RNA-Binding Protein that Regulates Spikelet Hull Length in Rice
LARGE GRAIN Encodes a Putative RNA-Binding Protein that Regulates Spikelet Hull Length in Rice
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DOI：
10.1093/pcp/pcz014
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发表时间：
2019-03-01
影响因子：
4.9
通讯作者：
Maekawa, Masahiko
中科院分区：
文献类型：
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作者：
Chiou, Wan-Yi;Kawamoto, Tadafumi;Maekawa, Masahiko
粒重是水稻产量构成因素之一，粒大小是决定粒重的关键因素。因此，要提高粮食产量，重要的是要阐明的详细机制，调节粒度。通过转座子展示和F2和F3的粒长与LGG基因型的共分离分析，发现了一个大粒（Lgg）突变体，该突变体是由编码RNA结合蛋白的LGG基因5个非翻译区的nDart 1 -3截短和355 bp缺失引起的。规则间隔的短回文重复序列/CRISPR相关9介导的LGG敲除和过表达分别导致比野生型更长和更短的谷粒，表明LGG调节小穗船体长度。LGG的表达量在0.6 mm长的幼穗中最高，并随着穗的伸长而逐渐降低。LGG在根和叶中也有表达。这些结果表明，LGG功能在穗发育的非常早期阶段。Lgg基因敲除和过表达植株的小穗壳纵向细胞数与野生型有显著差异，表明LGG基因可能调控小穗船体纵向细胞的增殖。从LGG敲除和过表达植物的1 mm长的幼穗的RNA-Seq分析显示，相对于LGG过表达植物和野生型，许多细胞周期相关基因的表达在敲除植物中降低，而一些细胞增殖基因在敲除植物中高度表达。这些结果表明，LGG可能是水稻颖花船体细胞周期和细胞分裂的调节因子。
Grain size is a key determiner of grain weight, one of the yield components in rice (Oryza sativa). Therefore, to increase grain yield, it is important to elucidate the detailed mechanisms regulating grain size. The Large grain (Lgg) mutant, found in the nonautonomous DNA-based active rice transposon1 (nDart1)-tagged lines of Koshihikari, is caused by a truncated nDart1-3 and 355 bp deletion in the 5 untranslated region of LGG, which encodes a putative RNA-binding protein, through transposon display and cosegregation analysis between grain length and LGG genotype in F2 and F3. Clustered regularly interspaced short palindromic repeats/CRISPR-associated 9-mediated knockout and overexpression of LGG led to longer and shorter grains than wild type, respectively, showing that LGG regulates spikelet hull length. Expression of LGG was highest in the 0.6-mm-long young panicle and gradually decreased as the panicle elongated. LGG was also expressed in roots and leaves. These results show that LGG functions at the very early stage of panicle development. Longitudinal cell numbers of spikelet hulls of Lgg, knockout and overexpressed plants were significantly different from those of the wild type, suggesting that LGG might regulate longitudinal cell proliferation in the spikelet hull. RNA-Seq analysis of 1-mm-long young panicles from LGG knockout and overexpressing plants revealed that the expressions of many cell cycle-related genes were reduced in knockout plants relative to LGG-overexpressing plants and wild type, whereas some genes for cell proliferation were highly expressed in knockout plants. Taken together, these results suggest that LGG might be a regulator of cell cycle and cell division in the rice spikelet hull.