Auxin signaling module OsSK41-OsIAA10-OsARF regulates grain yield traits in rice

Auxin is an important phytohormone in plants, and auxin signaling pathways in rice play key roles in regulating its growth, development, and productivity. To investigate how rice grain yield traits are regulated by auxin signaling pathways and to facilitate their application in rice improvement, we validated the functional relationships among regulatory genes such as OsIAA10, OsSK41, and OsARF21 that are involved in one of the auxin(OsIAA10) signaling pathways. We assessed the phenotypic effects of these genes on several grain yield traits across two environments using knockout and/or overexpression transgenic lines.Based on the results, we constructed a model that showed how grain yield traits were regulated by OsIAA10 and OsTIR1, OsAFB2, and OsSK41 and OsmiR393 in the OsSK41-OsIAA10-OsARF module and by OsARF21 in the transcriptional regulation of downstream auxin response genes in the OsSK41-OsIAA10-OsARF module. The population genomic analyses revealed rich genetic diversity and the presence of major functional alleles at most of these loci in rice populations. The strong differentiation of many major alleles between Xian/indica and Geng/japonica subspecies and/or among modern varieties and landraces suggested that they contributed to improved productivity during evolution and breeding. We identified several important aspects associated with the genetic and molecular bases of rice grain and yield traits that were regulated by auxin signaling pathways.We also suggested rice auxin response factor(OsARF) activators as candidate target genes for improving specific target traits by overexpression and/or editing subspecies-specific alleles and by searching and pyramiding the ‘best' gene allelic combinations at multiple regulatory genes in auxin signaling pathways in rice breeding programs.

水稻愈伤诱导过程中生长素通路的初步研究

构建水稻LBD基因家族中CRL1基因的CRISPR/CAS9基因敲除载体,并转化中花11水稻愈伤,获得了8个转基因片段缺失家系;对CRL1基因敲除材料种子进行愈伤诱导实验;结果显示,它们的愈伤组织诱导受到了强烈抑制,与已知的水稻OsIAA10基因的RNA干扰材料表型相似。进行OsIAA10的亚细胞定位实验,结果显示,OsIAA10同时定位在细胞核与细胞膜上。通过酵母双杂交筛库实验,发现OsIAA10能与OsARF家族成员中的OsARF5、OsARF1、OsARF721、OsARF23四个转录因子发生互作。以CRL1基因启动子为诱饵构建载体,进行酵母单杂交点对点实验,结果显示,这4个转录因子中只有OsARF5与OsARF21能特异性结合CRL1基因启动子区的AuxRE基序,激活CRL1基因转录。本研究结果初步证明水稻侧根发育通路与愈伤组织诱导过程存在直接相关,水稻与双子叶植物之间存在保守的生长素调控机制,在水稻种子的愈伤组织诱导过程中发挥着重要的作用。