Abstract: Plant height confers important effects on crop yield in rice, which is regulated by many aspects in the growth and development process. Ethylene is one of important factors for regulating plant growth and stress response. In this research, we identified a mutant D814 from the mutants insensitive to ethylene in roots growth. D814 mutants showed the dwarf phenotype, decreased effective tilling numbers and reduced 1000-grain weight. Map-based cloning indicated that D814 located in 1 cM range on chromosome 1, in which there contained six genes contributed to dwarf phenotype in the previous researches. Sequencing analyses demonstrated that OsBRI1（LOC_Os01g52050） has a point mutation at 1 837 bp downstream of ATG, in which the G is changed to T. There were two homologous genes of OsBRI1 in rice, OsBRL1 and OsBRL3, of which the sequences have no mutation in D814 mutants. A reported mutant of OsBRI1, gsor300084, also showed decreased sensitivity to ethylene in root. Due to the function of OsBRI1 was a receptor in brassinosteroid (BR) signal pathway, we found the expressions of BR-response genes were affected in D814, which indicated that D814 was an allele mutant of OsBRI1. Moreover, our analyses showed that D814 affected the expression levels of ethylene signaling-related genes and displayed increased salt tolerance. Thus our research provided a novel research material for exploring the molecular mechanism of ethylene regulating rice growth and stress tolerance, and laid a foundation for investigating the interplay of ethylene and brassinosteroid in growth and development.

Key words: rice, ethylene, dwarf, map-based cloning, salt stress response

摘要： 水稻株高对作物产量有着重要的影响，在水稻整个生长发育过程中，株高受到多因素的调控，而植物激素乙烯就是重要的影响因素之一。用10 mg/m3乙烯处理水稻幼苗，对水稻突变体库进行筛选，获得了3个根伸长生长对乙烯敏感性降低的突变体，其中1个突变体D814表现出植株矮化、分蘖数减少、千粒重下降等特征。图位克隆将其定位在1号染色体上1 cM的区间内，该区间有6个已报道的矮杆突变基因，通过对这6个基因测序，发现其中1个基因OsBRI1（LOC_Os01g52050）发生了点突变（编码区第1 837位G突变为T）。并在D814中分别对OsBRI1的2个同源基因（OsBRL1和OsBRL3）进行测序，发现这2个基因均无突变。利用已报道的OsBRI1等位突变体gsor300084进行乙烯处理，发现gsor300084与D814一样，表现出根对乙烯敏感性降低。OsBRI1是植物激素油菜素内酯（brassinosteroid，BR）的信号受体，经检测，BR信号途径响应基因在D814突变体中的表达也有变化，说明D814是OsBRI1的1个等位突变体。功能分析发现，D814参与乙烯信号转导调控途径和植物盐胁迫应答途径。研究结果为探究乙烯调控水稻生长发育及耐逆性的分子机理提供了研究材料，也为进一步探讨油菜素内酯与乙烯协同调控水稻生长发育机制奠定了理论基础。

关键词: 水稻, 乙烯, 矮杆, 图位克隆, 盐胁迫应答