核桃WD40转录因子JrATG18a基因的克隆及逆境响应

Identification and Stress Response Analysis of a WD40 Transcription Factor JrATG18a Gene from Juglans regia

WD40转录因子在植物逆境响应中具有重要作用。本研究克隆获得核桃的一条WD40家族的自噬相关蛋白(Autophagy-related protein)18a基因(JrATG18a),通过生物信息学和基因表达技术,分析不同非生物及植物激素处理下JrATG18a基因的表达规律,预测JrATG18a的基本生物功能。结果显示,JrATG18a的开放阅读框(ORF)为1371 bp,编码蛋白含456个氨基酸,分子量为50.746 k D,理论等电点为5.97。与草莓、苹果、碧桃等具有较近的进化关系。其启动子含有热激响应(HSE)、低温胁迫(LTR)、水杨酸(SA)响应等相关元件。表达分析发现JrATG18a基因在热、寒、旱、SA、茉莉酸甲酯(Me JA)、脱落酸(ABA)处理下能被不同程度的诱导,且体现出根和叶的表达差异。这些结果表明,JrATG18a基因能响应逆境参与核桃适应不良环境,可作为核桃抗逆分子育种的重要候选基因。

The WD40 protein,also known as WD-repeat protein,contains 6-16 copies of the conserved domain,starting from Gly-His to tryptophan-aspartate（ Trp-Asp,WD）. The WD40 protein contains numerous members and composed a transcription factor（ TF） family that plays important roles in plant responses to stress stimulus. Autophagyrelated protein is a type of WD40 TF involved in a variety of life activities such as plant growth,development,metabolism and response to adverse stimulus. However,the biological function of WD40 protein,especially the autophagy-related protein,was analyzed often in herbaceous plants,and its role on woody trees（ e. g. walnut） remained poorly illustrated. In order to better explore the resistance mechanism of walnut tree to abiotic stresses,here an autophagy-related protein 18 a（ ATG18 a） gene that belongs to WD40 TF was isolated from Juglans regia L.（ referred JrATG18a）. The JrATG18a gene contains a 1371-bp open reading frame（ ORF） that putatively encodes 456 amino acids,with a predicted molecular weight of 50. 746 k D and a theoretical isoelectric point of 5. 97. The phylogenic analysis revealed that JrATG18a grouped with the ATG proteins from Fragaria vesca L.,Malus domestica（ Suckow） Borkh.,and Prunus persica（ L.） Batsch.. The predicted three-dimensional structure of JrATG18a protein is similar to that of strawberry Fvv ATG18 a and apple Md ATG18 a,implying that JrATG18a may share similar functions with Fvv ATG18 a andMd ATG18 a. The 2090 bp upstream promoter segment contained several abiotic stress response cis-elements,such as heat shock element（ HSE）,low temperature response（ LTR）,and salicglic acid（ SA）. By quantitative real time PCR（ qRT-PCR）,the expression profiles of JrATG18a in root and leaf were analyzed,and this gene was inducible under heat,cold,drought,SA,Me JA,ABA treatments. These results suggested that JrATG18a might be involved in the response to abiotic stress in walnut,and possibly JrATG18a is an effective candidate gene for walnut molecular breeding.