Sun Hongzheng, Peng Ting, Zhao Yafan, Du Yanxiu, Zhang Jing, Li Junzhou, Xin Zeyu, Zhao Quanzhi
Collaberative Innovation Center of Henan Grain Crops, Henan Agricultural University, Zhengzhou, China; Rice Engineer Center, Henan Agricultural University, Zhengzhou, China; Key Laboratory of Physiology, Ecology and Genetics Improvement of Food Crop in Henan Province, Henan Agricultural University, Zhengzhou, China.
PLoS One. 2015 Sep 10;10(9):e0137168. doi: 10.1371/journal.pone.0137168. eCollection 2015.
Poor grain filling of inferior grains located on lower secondary panicle branch causes great drop in rice yield and quality. Dynamic gene expression patterns between superior and inferior grains were examined from the view of the whole transcriptome by using RNA-Seq method. In total, 19,442 genes were detected during rice grain development. Genes involved in starch synthesis, grain storage and grain development were interrogated in particular in superior and inferior grains. Of the genes involved in sucrose to starch transformation process, most were expressed at lower level in inferior grains at early filling stage compared to that of superior grains. But at late filling stage, the expression of those genes was higher in inferior grains and lower in superior grains. The same trends were observed in the expression of grain storage protein genes. While, evidence that genes involved in cell cycle showed higher expression in inferior grains during whole period of grain filling indicated that cell proliferation was active till the late filling stage. In conclusion, delayed expression of most starch synthesis genes in inferior grains and low capacity of sink organ might be two important factors causing low filling rate of inferior grain at early filling stage, and shortage of carbohydrate supply was a limiting factor at late filling stage.
着生在二次枝梗下部的弱势籽粒灌浆不良会导致水稻产量和品质大幅下降。采用RNA-Seq方法，从全转录组角度研究了强势粒与弱势粒之间的动态基因表达模式。在水稻籽粒发育过程中，共检测到19442个基因。特别对参与淀粉合成、籽粒贮藏和籽粒发育的基因在强势粒和弱势粒中进行了分析。在参与蔗糖向淀粉转化过程的基因中，大多数基因在灌浆初期在弱势粒中的表达水平低于强势粒。但在灌浆后期，这些基因在弱势粒中的表达较高，而在强势粒中的表达较低。籽粒贮藏蛋白基因的表达也呈现相同趋势。同时，参与细胞周期的基因在籽粒灌浆全过程中在弱势粒中表达较高，这表明细胞增殖一直活跃到灌浆后期。综上所述，弱势粒中大多数淀粉合成基因表达延迟以及库器官能力较低可能是灌浆初期弱势粒充实率低的两个重要因素，而碳水化合物供应不足是灌浆后期的限制因素。
