PstVosA1转录因子基因在调控小麦条锈菌耐高温反应中的生物学功能分析

Analyses on biological functions of a transcription factor gene PstVosA1 in regulating thermotolerance responses of Puccinia striiformis f. sp. tritici

小麦条锈病是典型的冷凉生态区气传真菌病害,病原菌在越夏易变区(即秋季菌源基地)的越夏情况决定了冬季繁殖区条锈菌的初侵染菌源。小麦条锈病的发生流行极易受到温湿度关键气象因子的影响。近年来的调查研究发现,我国小麦条锈菌越夏海拔下限逐年下降,且越夏区范围进一步扩大,说明条锈菌耐高温胁迫能力增强,给未来小麦条锈病流行规律研究及制定防治策略带来了全新挑战。真菌特有的Velvet转录因子家族中VosA基因参与了真菌生长发育和次生代谢的调控,但关于该转录因子在条锈菌耐高温性中的作用却知之甚少。实时荧光定量PCR分析发现,温度敏感菌系蓬9和耐高温菌系A4在侵染寄主过程中PstVosA1基因均受高温胁迫诱导表达,但耐高温菌系PstVosA1相对表达水平明显高于温度敏感菌系蓬9。利用寄主诱导的基因沉默技术(HIGS)沉默小麦条锈菌耐高温菌系A4中的PstVosA1基因能显著降低在高温(21℃)接种条件下的平均发病严重度、孢子堆密度和生物量。研究结果说明PstVosA1基因正调控小麦条锈菌耐高温胁迫反应过程,增加该基因的表达水平,有利于增强小麦条锈菌耐高温性。

Wheat stripe(yellow) rust is a typical cool-ecological airborne fungal disease. It was found that after oversummering, Puccinia striiformis f. sp. tritici(Pst) at the autumn determines the primary inoculum sources in the disease winter-increasing areas. The epidemic outbreaks of wheat stripe rust are greatly influenced by the environmental key factors such as temperature and humidity. The disease investigations in recent years found that the minimum altitude of oversummering regions of Pst become lower year by year and its oversummering areas extended more widely, indicating that the thermotolerant capability of Pst has been improving greatly. Thus, wheat stripe rust epidemics study and the development of control strategy would face new challenge. The gene VosA, a member of fungus-specific Velvet transcription factor family, involves in regulation of fungal development and secondary metabolism, but little is known about its roles in regulating fungal thermotolerance. Real-time quantitative PCR analysis indicated that PstVosA1 expression was induced under high temperature during the infecting course both in thermotolerant isolate A4 and temperature sensitive isolate Peng 9, and the significantly higher expression level was detected in the tolerant one. Silencing of the PstVosA1 in the thermotolerant isolate A4 with host induced gene silencing(HIGS) approach led to significant reduce on average disease severity, uredium density and fungal biomass when inoculation at high temperature(21℃). These results showed that the PstVosA1 positively regulated thermotolerance responses, and increasing the expression level could promote thermotolerant capability in Pst.