β-氨基丁酸早期诱导表达基因StWRKY5参与马铃薯晚疫病抗性

An Early β-a minobutyric Acid Responsive Gene StWRKY5 Confers Resistance to Late Blight in Potato

β-氨基丁酸(β-aminobutyric acid,BABA)诱导能够增强马铃薯对晚疫病的抗性。本研究从马铃薯中克隆了一个WRKY转录因子家族的基因St WRKY5。c DNA-AFLP表达谱研究表明,BABA(2 mmol/L)处理马铃薯6 h后该基因明显上调表达,晚疫病菌(Phytophthora infestans)接种16 h后上调表达。半定量RT-PCR检测表明水杨酸SA(10μmol/L)处理马铃薯离体叶片4 h后该基因上调表达,茉莉酸甲酯Me JA(50μmol/L)诱导12 h后开始表达,机械伤害处理24 h后,该基因表达也会增强,表明该基因参与多种生物和非生物因子的胁迫反应。通过稳定转化获得了超量表达St WRKY5的转基因马铃薯株系。采用离体叶片接种鉴定方法对转基因马铃薯株系晚疫病抗性进行了鉴定,研究结果显示接种4 d后超量表达转基因株系其病斑面积均显著小于对照,表明在马铃薯中超量表达St WRKY5提高了晚疫病抗性。

Abs tract In potato, high level of resistance against Phytophthora infestans can be induced by exogenous application of β-aminobutyric acid(BABA). In this study, a BABA early induced St WRKY5 gene was cloned from potato. cDNA-AFLP analysis indicated that St WRKY5 expression can be induced by BABA(2 mmol/L) as early as6 h, while St WRKY5 up regulated 16 h after P. infestans inoculation. Meanwhile semi-quantitative RT-PCR results showed that St WRKY5 was up-regulated 4 h after Salicylic acid(SA, 10 μmol/L) inducing and 12 h after Methyl-Jasmonate(Me JA, 50 μmol/L) treatment. St WRKY5 also responses to mechanical wound. The expression tests indicated that St WRKY5 may participate in multiple biotic and abiotic stresses. In addition, stable overexpression transgenic potato lines of St WRKY5 were produced. Detached leave assay was used to test late blight resistance of transgenic lines. The results indicated that the disease lesion sizes on the leaves of over expression lines is significantly smaller than that of control, indicating that over expression of St WRKY5 in potato enhances late blight resistance.