储成才，李家洋院士组最新PNAS文章

　　

　　种子大小是水稻产量构成的要素之一，长期以来一直是很多作物育种改良的重要目标。生长素作为最为重要的植物激素之一，参与了植物生长发育的众多重要过程。尽管生长素的合成、运输和信号转导在模式植物拟南芥中研究已比较深入，然而其在作物中的研究和对作物产量的影响仍知之甚少。

　　中国科学院遗传与发育生物学研究所植物基因组学国家重点实验室储成才研究员和其合作者李家洋院士课题组通过对一水稻大粒显性突变体(Big grain1, Bg1-D)的研究，发现BG1编码一个受生长素特异诱导的早期响应的未知功能蛋白，在水稻茎和穗的维管组织中特异表达。有意思的是，BG1过表达株系生长素极性运输能力显著增强，并导致水稻籽粒显著增大。田间试验表明，BG1过量表达株系与对照相比千粒重增加25%，产量增加21%。BG1过量表达植株生物量也显著提高。进化分析表明BG1在高等植物中具有高度保守性。过表达BG1同样使双子叶植物拟南芥种子增大及生物量增加，暗示BG1在单、双子叶植物生物量及作物产量改良中均具有极大的应用潜力。

　　该项研究成果于2015年8月17日在美国科学院院刊（PNAS）在线发表（doi:10.1073/pnas.1512748112）。刘林川博士和童红宁副研究员为论文共同第一作者，研究得到国家自然科学基金、农业部转基因专项等资助。

　　BG1可显著提高水稻及拟南芥的生物量和产量

原文摘要：

Activation of Big Grain1 significantly improves grain size by regulating auxin transport in rice

Grain size is one of the key factors determining grain yield. However, it remains largely unknown how grain size is regulated by developmental signals. Here, we report the identification and characterization of a dominant mutant big grain1 (Bg1-D) that shows an extra-large grain phenotype from our rice T-DNA insertion population. Overexpression of BG1 leads to significantly increased grain size, and the severe lines exhibit obviously perturbed gravitropism. In addition, the mutant has increased sensitivities to both auxin and N-1-naphthylphthalamic acid, an auxin transport inhibitor, whereas knockdown of BG1 results in decreased sensitivities and smaller grains. Moreover, BG1 is specifically induced by auxin treatment, preferentially expresses in the vascular tissue of culms and young panicles, and encodes a novel membrane-localized protein, strongly suggesting its role in regulating auxin transport. Consistent with this finding, the mutant has increased auxin basipetal transport and altered auxin distribution, whereas the knockdown plants have decreased auxin transport. Manipulation of BG1 in both rice and Arabidopsis can enhance plant biomass, seed weight, and yield. Taking these data together, we identify a novel positive regulator of auxin response and transport in a crop plant and demonstrate its role in regulating grain size, thus illuminating a new strategy to improve plant productivity.