中文摘要：黄曲霉，一种条件致病菌，通过致癌的黄曲霉毒素(AFs)污染玉米及其它主要农作物。除AFs外，还研究过黄曲霉产生的更多的次生代谢物(SMs)对昆虫及脊椎动物的毒性。但是SMs对黄曲霉入侵寄主植物的作用尚待研究。环匹阿尼酸(CPA)，一种黄曲霉产生的毒害神经的SM，是一种植物内质网钙ATP酶(ECAs)的纳摩尔抑制剂及细胞死亡诱导剂。本研究假设由于其细胞毒性，CPA作为一个重要的致病因素，它杀死植物细胞并支持真菌的腐生生活方式而影响宿主防御反应，并用两种互补方法进行了检验。研究结果表明i)CPA作为一个重要的致病因素使黄曲霉能进行腐生ii)玉米自交系对CPA的耐受性不同。利用这种自然变异，当前我们开展全基因组和候选基因的方法确定抗玉米曲霉穗腐病的新成份。
外文摘要：Aspergillus flavus, an opportunistic pathogen, contaminates maize and other key crops with carcinogenic aflatoxins (AFs). Besides AFs, A. flavus makes many more secondary metabolites (SMs) whose toxicity in insects or vertebrates has been studied. However, the role of SMs in the invasion of plant hosts by A. flavus remains to be investigated. Cyclopiazonic acid (CPA), a neurotoxic SM made by A. flavus, is a nanomolar inhibitor of endoplasmic reticulum calcium ATPases (ECAs) and a potent inducer of cell death in plants. We hypothesized that CPA, by virtue of its cytotoxicity, may serve as a key pathogenicity factor that kills plant cells and supports the saprophytic life style of the fungus while compromising the host defense response. This proposal was tested by two complementary approaches. A comparison of CPA levels among A. flavus isolates indicated that CPA may be a determinant of niche adaptation, i.e., isolates that colonize maize make more CPA than those restricted only to the soil. Further, mutants in the CPA biosynthetic pathway are less virulent in causing ear rot than their wild-type parent in field inoculation assays. Additionally, genes encoding ECAs are expressed in developing maize seeds and are induced by A. flavus infection. Building on these results, we developed a seedling assay in which maize roots were exposed to CPA, and cell death was measured as Evans Blue uptake. Among >40 maize inbreds screened for CPA tolerance, inbreds with proven susceptibility to ear rot were also highly CPA sensitive. The publicly available data on resistance to silk colonization or AF contamination for many of the lines was also broadly correlated with their CPA sensitivity. In summary, our studies show that i) CPA serves as a key pathogenicity factor that enables the saprophytic life style of A. flavus and ii) maize inbreds are diverse in their tolerance to CPA. Taking advantage of this natural variation, we are currently pursuing both genome-wide and candidate gene approaches to identify novel components of maize resistance to Aspergillus ear rot.
作者：Chalivendra, SC；DeRobertis, C；Chang, PK；Damann, KE
作者单位：Louisiana State Univ
期刊名称：MOLECULAR PLANT-MICROBE INTERACTIONS
期刊影响因子：4.145
出版年份：2017
出版刊次：5
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