棉花GhRAR1基因调控棉花抗黄萎病机理的研究

Mechanism of the cotton GhRAR1 gene regulating the resistance of cotton to Verticillium wilt

棉花黄萎病是一种严重影响棉株生长的土传维管束真菌病害。挖掘抗性基因,解析抗病机制,对创制棉花抗病种质防御棉花黄萎病具有重要意义。本研究从抗病棉花品种‘中植棉2号’中获得GhRAR1基因,采用病毒诱导的基因沉默(VIGS)技术、基因过表达及qRT-PCR技术探究GhRAR1介导的棉花抗黄萎病机制。结果表明,GhRAR1的表达受棉花黄萎病菌诱导。GhRAR1沉默棉株对黄萎病菌敏感性增强,表现为植株病情指数升高、叶片萎蔫、茎部维管束组织褐变加重。GhRAR1沉默棉株中活性氧(ROS)生成基因GhRbohD表达量低,H_(2)O_(2)积累量少。过表达GhRAR1基因的拟南芥植株对棉花黄萎病抗性增强,AtRbohD表达量高,H_(2)O_(2)积累量多,发生过敏反应(HR),菌丝扩散被抑制。推测GhRAR1可能调控ROS积累和HR,从而介导棉花对黄萎病菌的抗性。

Cotton Verticillium wilt is a soil-borne vascular fungal disease,which seriously affects the growth of cotton.Mining resistance genes and exploring disease resistance mechanism are essential for innovating cotton disease-resistant germplasms and controlling cotton Verticillium wilt.Here,we cloned GhRAR1 from the disease-resistant cultivar‘Zhongzhimian 2’,and VIGS,overexpression techniques and qRT-PCR were used to explore the potential mechanism of GhRAR1-mediating defense against Verticillium wilt.The results showed that GhRAR1 was up-regulated in cotton plants inoculated with Verticillium dahliae.When GhRAR1 was knocked down,cotton plants were more susceptible to V.dahliae than the control,with the increase of plant disease index,leaf wilting and heavy browning of vascular bundle tissue in the stem.Furthermore,GhRAR1-silenced cotton seedlings showed lower expression of GhRbohD,and less accumulation of H_(2)O_(2)than the control.When GhRAR1 was overexpressed in Arabidopsis thaliana,the plants exhibited enhanced resistance to V.dahliae.GhRAR1-overexpressed A.thaliana plants showed higher expression of AtRbohD,more accumulation of H_(2)O_(2)than wild-type A.thaliana,and appeared hypersensitive response(HR),thereby inhibited the spread of hyphae.Taken together,our study indicates that GhRAR1 may be involved in regulating ROS accumulation and HR production for the resistance of cotton plants to V.dahliae.