玉米转录因子NAC78的克隆及表达特性分析

Gene Cloning and Expression Analysis of Transcription Factor NAC78 in Maize

NAC(NAM,ATAF1/2,CUC2)家族转录因子在调控植物生长发育、响应逆境胁迫及激素信号转导等方面起着重要作用,探究其功能可为解析玉米对逆境的响应机制提供基础。通过RT-PCR克隆得到了玉米转录因子NAC78的CDS序列,通过生物信息学方法分析NAC78的特点,用荧光定量检测了NAC78的组织表达特性及对逆境胁迫的响应情况。结果显示,NAC78基因的开放阅读框长1 830 bp,编码609个氨基酸,蛋白分子量为67.45 kD,等电点5.19。NAC78蛋白质N端含有一个保守的NAM结构域,由8个α螺旋和7个β片层构成。进化树分析结果表明NAC78与谷子NAC86亲缘关系最近。NAC78在玉米各组织中均表达,在胚乳中的表达量显著高于其他组织;在胚乳发育的过程中,NAC78的表达变化呈现先增加后降低的趋势,授粉后15 d的相对表达量较第5天增加52.52倍;NAC78的表达受到ABA、NaCl和PEG的诱导,在3种处理下均呈现先增加后降低的趋势,在ABA处理籽粒6 h后相对表达量较0 h增加了11.4倍,NaCl和PEG处理植株6 h后在叶片中的相对表达量分别增加了1.87和2.69倍。NAC78在玉米胚乳中表达量显著高于其他组织,并对ABA、NaCl和PEG处理有不同程度的响应。

NAC(NAM,ATAF1/2,CUC2)family transcription factors play an important role in regulating plant growth and development,responding to stress and hormone signal transduction.Exploring their functions will provide bases for analyzing the stress response mechanism in maize.The CDS sequence of the NAC78 was cloned by RT-PCR,the characteristics of the NAC78 were analyzed by bioinformatics method,and the expression patterns of NAC78 in different tissues and its responses to stresses were detected by real-time quantitative PCR.The length of NAC78’s open reading frame was 1830 bp,encoding 609 amino acids.Its molecular weight was 67.45 kD,and isoelectric point was 5.19.The N-terminal of the NAC78 protein contained a conserved NAM domain,consisting of 8α-helices and 7β-sheets.The results from phylogenetic tree analysis showed that NAC78 was most closely related to the NAC86 in Setaria italica.The results of real-time quantitative PCR showed that NAC78 expressed in all tissues of maize,and the expression in the endosperm was significantly higher than that in other tissues;the expression of NAC78 increased first and then decreased,and the relative expression increased by 52.52 times compared with that on the day 5.The expression of NAC78 was induced by ABA,NaCl and PEG,which increased first and then decreased under three stress treatments,and the relative expression in the seeds increased by 11.4 times after 6 h compared with that of 0 h under ABA treatment,and the those in the leaves treated with NaCl and PEG increased by 1.87 and 2.69 times after 6 h,respectively.In sum,the expression of NAC78 in the endosperm of maize is significantly higher than that in other tissues,and presents varied responses to ABA,NaCl and PEG treatment.