Factors governing the regulation of Sclerotinia sclerotiorum cutinase A and polygalacturonase 1 during different stages of infection
Factors governing the regulation of Sclerotinia sclerotiorum cutinase A and polygalacturonase 1 during different stages of infection
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DOI：
10.1139/w2012-031
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发表时间：
2012-05-01
影响因子：
2.8
通讯作者：
Hegedus, Dwayne D.
中科院分区：
文献类型：
--
作者：
Bashi, Zafer Dallal;Rimmer, S. Roger;Hegedus, Dwayne D.
核盘菌释放水解酶，从而降解植物角质层、中层、初生和次生细胞壁。角质层被发现是对核盘菌感染的屏障，因为剥离表皮层蜡质的叶子更快地定植。因此，对编码多聚半乳糖醛酸酶1(SsPG1)和一种新发现的角质酶(SsCUTA)的基因的调控因素进行了研究。在体外，SsCutA转录本在叶片接种后1h内检测到，表达主要受菌丝与固体表面接触的影响。SsPg1的表达通过接触包括叶片在内的固体表面而适度诱导，并且随着感染的进展，表达仅限于病损的扩展边缘。糖饥饿诱导SsPg1表达，半乳糖醛酸抑制SsPg1表达。葡萄糖支持基础水平的SsPg1表达，但当提供给用于接种叶片的菌丝体时，其表达增强。这些观察结果与先前的报道相反，即葡萄糖抑制了SsPg1的表达，而半乳糖醛酸诱导了SsPg1的表达。药理学研究表明，钙信号的干扰影响了SsCutA和SsPg1的表达，并降低了菌核菌的毒力，而cAMP水平的升高降低了毒力，但不影响基因表达。讨论了在感染的不同阶段协调菌核葡萄球菌水解酶表达的机制。
Sclerotinia sclerotiorum releases hydrolytic enzymes that sequentially degrade the plant cuticle, middle lamellae, and primary and secondary cell walls. The cuticle was found to be a barrier to S. sclerotiorum infection, as leaves stripped of epicuticular wax were more rapidly colonized. Consequently, the factors affecting the regulation of genes encoding polygalacturonase 1 (SsPG1) and a newly identified cutinase (SsCUTA) were examined. In vitro, SsCutA transcripts were detected within 1 h postinoculation of leaves, and expression was primarily governed by contact of mycelia with solid surfaces. Expression of SsPg1 was moderately induced by contact with solid surfaces including the leaf, and expression was restricted to the expanding margin of the lesion as the infection progressed. SsPg1 expression was induced by carbohydrate starvation but repressed by galacturonic acid. Glucose supported a basal level of SsPg1 expression but accentuated expression when provided to mycelia used to inoculate leaves. These observations were contrary to earlier reports indicating that glucose repressed SsPg1 expression while galacturonic acid induced expression. Pharmacological studies showed that disruption of calcium signalling affected SsCutA and SsPg1 expression and decreased S. sclerotiorum virulence, whereas elevated cAMP levels reduced virulence without affecting gene expression. The mechanisms involved in coordinating the expression of S. sclerotiorum hydrolytic enzymes throughout the various stages of the infection are discussed.