玉米SNAC基因的遗传变异及耐旱性调控

摘要

以我国玉米育种中常用的16份自交系为材料,通过对SNAC(Stress-responsive NAM,ATAF1/2,CUC2)基因编码区及上游启动子区800 bp核苷酸序列进行测序,检测SNAC基因在不同杂种优势类群材料中的遗传变异.在12个SNAC基因中,其中有4个基因在上游800 bp区检测到遗传变异,有4个基因变异位点超过30个,多态性较高.虽然大多数SNAC基因变异以SNP(Single nucleotide polymorphism)为主,但在ZmNAC031467基因中检测到较多的插入缺失变异(InDel),达到基因总遗传变异的63.3%.通过PLACE软件对上游启动子有变异的4个基因进行3种耐逆结合元件的预测,结果显示4个基因均含有3种耐逆结合元件,但是基因突变对启动子结合元件的影响较小.再对检测到的遗传变异进行核苷酸多态性分析和中性检验,有7个SNAC基因核苷酸多态性较高,其中ZmNAC080308基因的多态性达到0.00962,推测这些基因在遗传漂移过程中受自然选择影响较大.利用t检验初步发现ZmNAC070395和ZmNAC080398基因的2个变异位点与耐旱相关性状关联,为进一步分析SNAC基因核苷酸变异与耐旱性状的关系提供一定的借鉴.%The coding regions and their upstream 800 bp promoter regions of SNAC genes (Sress-responsive NAM, ATAF1/2, CUC2) were sequenced in 16 maize inbred lines commonly used in China. Among 12 SNAC genes, genetic variations in promoter region were only identified in four SNAC genes, and more than 30 variations were identified in four SNAC genes, showing higher polymorphism in the four genes than other in SNAC genes. Although most of the SNAC genes were mainly SNP (Single nucleo-tide polymorphism) mutations, more insertion/deletion mutations were detected in ZmNAC031467 gene, reaching 63.3% of the total genetic variations. The PLACE software was used to predict three kinds of stress-tolerant binding elements in SNAC gene, but little effect was found to be related with the variations. Additionally, high nucleotide polymorphisms were identified in seven SNAC genes, especially with the highest π value of 0.00962 in ZmNAC030308, which suggested that they were greatly influenced by natural selection in the genetic drift. With the t-test, two mutations of ZmNAC070395 and ZmNAC080398 genes were associated with drought-tolerant traits, which provides references for further analysing the relationship between nucleotide variation in SNAC and drought tolerance traits.