过量表达紫花苜蓿MsHB7基因对拟南芥耐旱性的影响

同源异型域-亮氨酸拉链蛋白（HD-Zip）第I类亚家族在植物非生物胁迫调控过程中起着重要作用，已在多个物种中进行了克隆鉴定，但关于紫花苜蓿该家族基因的研究还鲜有报道。本研究旨在研究紫花苜蓿HD-Zip第I类亚家族基因MsHB7对拟南芥抗旱性的调控功能。通过克隆得到大小为738 bp、编码245个氨基酸的MsHB7基因的开放阅读框。多重序列比对和系统进化树分析结果显示，MsHB7蛋白属于HD-Zip I亚家族，且与拟南芥中ATHB7和ATHB12亲缘关系较近。实时荧光定量分析表明，MsHB7基因受干旱诱导。将MsHB7基因转化拟南芥并获得了阳性植株。干旱处理后，转基因拟南芥比野生型拟南芥萎蔫程度更明显，转基因植株相对含水量显著低于野生型拟南芥，并积累了更多的脯氨酸和丙二醛。qRT-PCR检测发现处理之后逆境胁迫指示基因ATCAT1、 ATDREB2A和ATRD29A在转基因拟南芥中的表达量显著升高，而ATLEA3的表达量显著下降。上述结果表明MsHB7基因的过表达可降低转基因拟南芥的耐旱性，为进一步开发利用该基因提供理论依据。

Effect of overexpression of the alfalfa MsHB7 gene on drought tolerance of Arabidopsis

The homeodomain-leucine zipper(HD-Zip)protein subfamily I plays an important role in the regulation of plant abiotic stress.There are few reports of HD-Zip I genes in alfalfa,although they have been cloned and identified in many species.The purpose of this study was to investigate the role of MsHB7,a HD-Zip I gene from alfalfa,in the regulation of Arabidopsis thaliana drought resistance.The MsHB7 gene with an open reading frame of 738 bp and encoding 245 amino acids was obtained by cloning.Multiple sequence alignment and phylogenetic tree analysis showed that MsHB7 belonged to the HD-Zip I subfamily and was closely related to ATHB7 and ATHB12 in A.thaliana.Real-time fluorescence quantitative analysis showed that the MsHB7 gene was induced by drought.The MsHB7 gene was transformed into A.thaliana and positive plants were obtained.After drought treatment,the transgenic A.thaliana wilted more obviously.The relative water content of transgenic plants was significantly lower than that of wild-type A.thaliana,and the proline and malondialdehyde levels accumulated in transgenic plants were more than wild-type.qRT-PCR results showed that the expression levels of stress response genes ATCAT1,ATDREB2A and ATRD29A in the transgenic A.thaliana were significantly increased,while the expression levels of ATLEA3 were significantly decreased after stress.The above results indicate that the overexpression of MsHB7 gene can reduce the drought tolerance of transgenic A.thaliana,which provides theoretical information as a basis for the further development and utilization of this gene.