白粉病菌侵染对美洲南瓜不同抗性品种PAL基因表达量的影响

Effects of Podosphaera xanthii Infection on Expression of PAL Gene in Different Resistant Varieties of Cucurbita pepo

为明确白粉病菌侵染对不同美洲南瓜抗性品种PAL基因表达量的影响,采用室内接种和qRTPCR技术分别测定不同美洲南瓜抗性品种接种苍耳单囊白粉菌后发病率和病情指数,并分析接菌后其不同组织部位PAL基因表达量的变化情况。室内测定结果表明,抗病品种小三星F2发病率和病情指数显著低于感病品种金12F2,尤其接菌后第13天,小三星F2发病率和病情指数分别为17.3%和15.6,而金12F2发病率和病情指数分别为93.3%和83.0。PAL基因表达量测定结果表明,不同抗性美洲南瓜接菌后,PAL基因相对表达量显著升高,且随着接种天数增加,其不同组织部位PAL基因相对表达量呈现出先增加后降低的趋势。抗病品种小三星F2接菌后叶片中PAL基因相对表达量增加较为显著,叶柄和茎秆次之,并且其相对表达量分别在第7和第9天达到最大值;感病品种金12F2接菌后叶片中PAL基因相对表达量较抗病品种低,但与对照相比,其PAL基因相对表达量显著增加,并分别在第9和第11天达到最大值。因此,PAL基因相对表达量与美洲南瓜抗白粉病强弱具有密切的关系。本研究可为南瓜抗病品种的选育提供科学依据。

To determine the effect of Podosphaera xanthii infection on PAL gene expression in different resistant varieties of Cucurbita pepo. The disease incidence,index and changes of PAL gene expression in different resistant varieties of Cucurbita pepo tissue were determined and analysed by the methods of in vitro inoculation and qRT-PCR technology after inoculated with the pathogen of Podosphaera xanthii,respectively. In vitro inoculation results showed that the disease incidence and index of Xiaosanxing F2 were significantly lower than the susceptible varieties of Jin12F2. Especially the disease incidence and index of Xiaosanxing F2 were 17. 3% and 15. 6 at 13 days after inoculation,and disease incidence and index of Jin12F2 were 93. 3% and 83. 0,respectively. The results of PAL gene expression showed that the relative expression of PAL gene was significantly improved after inoculated with the pathogen of Podosphaera xanthii in different resistant varieties of Cucurbita pepo in vitro. Also,the relative expression of PAL gene increased in different tissues and different varieties with the inoculation days increased at initial stage,but decreased in later. The relative expression of PAL gene in the leaves of disease-resistant varieties of Xiaosanxing F2 was significantly increased after inoculated with Podosphaera xanthii,but the petiole and stem were slightly increased compared with the leaves. The maximum relative expression quantity of PAL gene was at 7 and 9 days after inoculation in vitro; The relative expression of PAL gene in the leaves of susceptible varieties of Jin12F2 was lower than the disease-resistant varieties of Xiaosanxing F2 after inoculated with Podosphaera xanthii,but the relative expression of PAL gene increased significantly,compared with control. The maximum relative expression quantity was at 9 and 11 days. Therefore,relative expression of PAL gene is closely related to the disease resistance in Cucurbita pepo. Moreover,it can provide some theory foundation for breeding resistant varieties of pumpkin in the future.