禾谷镰刀菌FgNST1对FgMGV1及DON毒素合成的影响

Effects of Fusarium graminearum FgNST1 on FgMGV1 and the synthesis of DON toxin

为探究盐胁迫调控因子和促分裂素原活化蛋白激酶(mitogen activated protein kinases,MAPK)信号途径对盐胁迫的响应,以禾谷镰刀菌(Fusarium graminearum)为研究对象,应用生物信息学对禾谷镰刀菌FgNST1和FgMGV1保守域及其同源蛋白进行分析,采用酵母双杂交和荧光定量PCR分析了FgNST1和FgMGV1之间的相互关系,并检测了FgNST1基因对DON毒素的影响。结果表明,FgNST1含有盐胁迫负调控因子保守域,FgMGV1含有丝氨酸/苏氨酸蛋白激酶催化中心(Serine/Threonine protein kinase catalytic center,STKc)保守域;FgNST1与黄色镰刀菌的胁迫反应蛋白相似度最高。FgNST1与FgMGV1可以相互作用,在盐胁迫下FgNST1基因表达下调,而FgMGV1基因表达上调。在无盐胁迫下FgMGV1基因在FgNST1敲除突变体中几乎不表达,在盐胁迫下FgMGV1基因在FgNST1敲除突变体中的相对表达量高于野生型菌株。盐胁迫抑制禾谷镰刀菌在小麦基质中的脱氧雪腐镰刀菌烯醇(deoxynivalenol,DON)毒素合成。在无盐胁迫的小麦基质培养基中,FgNST1敲除突变体在产毒初期产生的DON毒素显著高于野生型,7 d后则显著低于野生型;在盐胁迫的小麦基质中,FgNST1敲除突变体产生的DON毒素始终高于野生型菌株。

To explore the response of salt stress regulatory factors and MAPK(mitogen activated protein kinases)signal pathways to salt stress,Fusarium graminearum was used as research material.The conserved domain and homologous proteins of NST1(negative for salt tolerance)and MGV1(map kinase for growth and virulence 1)of Fusarium graminearum were analyzed based on the bioinformatics.The relationship between FgNST1 and FgMGV1 was revealed by yeast two-hybrid and fluorescent quantitative PCR.The effect of FgNST1 on DON toxin synthesis was also detected.The results showed that the FgNST1 contained the conserved domain of salt stress negative regulator factors,and the FgMGV1 contained the conserved domain of Serine/Threonine protein kinase catalytic center(STKc).FgNST1 had the highest similarity with the stress response protein of Fusarium culmorum.FgNST1 could interact with FgMGV1.The gene expression level of FgNST1 was down-regulated under salt stress,while the FgMGV1 was up-regulated.FgMGV1 was hardly expressed in FgNST1 knockout mutants in the absence of salt stress,but the expression level of FgMGV1 was higher than that in the wild type under salt stress.DON toxin assay indicated that the salt stress inhibited the DON toxin synthesis in wheat substrates.Without salt stress in wheat matrix,the FgNST1 knockout mutant produced DON toxin significantly higher than the wild type at initial stage,but was obviously lower than the wild type after 7 days.Under salt stress in wheat matrix,the FgNST1 knockout mutant always produced higher DON toxin than the wild type.