玉米转录因子ZmbHLH54的克隆及其响应干旱胁迫的功能OA

[Objective]To identify a novel drought-responsive gene,ZmbHLH54,belonging to the basic Helix-Loop-Helix(bHLH)transcription factor family,and to investigate the response mechanism of this gene in a drought-stressed environment.[Method]Bioinformatics approaches were employed to systematically analyze the gene structure,protein characteristics,phylogenetic relationships,con-served motifs,and promoter cis-acting elements.Furthermore,the phenotypic identification of gene mutant material was conducted under drought stress conditions.The activities of superoxide dismutase(SOD)and peroxidase(POD)were measured,and the expression levels of relevant genes were quanti-fied using real-time fluorescent quantitative PCR(RT-qPCR).These analyses provided preliminary insights into the mechanisms underlying drought resistance.[Result]The ZmbHLH54 gene has a typi-cal bHLH domain and belongs to the bHLH transcription factor family.The coding region is 690bp,encoding 229 amino acids.There are several elements related to hormone and drought stress response in promoter region.ZmbHLH54 is a hydrophilic protein without transmembrane helical structure.After 5 days of drought stress,the negative control plants showed obvious leaf curling and wilting,while most mutant seedlings still kept the leaf stretch state or only slightly curling.Under drought stress,SOD and POD activities in zmbhlh54 mutant were significantly higher than those in the negative control.Furthermore,the expression of reactive oxygen species(ROS)scavenging genes(ZmSOD3 and ZmSOD4)was up-regulated in zmbhlh54 mutant,while the expression of ROS-related gene(Zm00001d036557)was suppressed.[Conclusion]The bHLH transcription factor family ZmbHLH54 may mainly respond to drought stress by regulating ROS clearance mechanism under drought stress,and enhances drought resistance of mutant at seedling stage.