温室条件下条形柄锈菌体细胞重组的分子确证

Molecular identification of somatic recombination of stripe rust pathogen(Puccinia striiformis) in the greenhouse

为了获得温室条件下条形柄锈菌发生体细胞重组而导致毒性变异的直接证据,本研究选取7个美国条形柄锈菌小麦专化型菌系和2个美国条形柄锈菌大麦专化型菌系按照夏孢子颜色和专化型与毒性差异组成9对菌系组合,对于室内混合接种产生的子代菌系用具有不同抗性的小麦或大麦品种进行筛选,采用毒性分析及SSR分子标记技术对条形柄锈菌体细胞重组现象进行了研究。对获取的413个单孢子代菌系进行的毒性分析结果显示,有84个单孢子代菌系的毒性谱表现与亲本菌系不同,初步证明体细胞重组过程的存在。SSR标记分析结果显示,11对SSR引物中有6对引物在5对菌系组合的28个毒性谱不同的单孢子代菌系中,检测发现3个单孢菌系的扩增条带与其亲本菌系不同,且表现为亲本菌系扩增条带的重组,为体细胞重组菌系。这一结果从分子水平上证明了条形柄锈菌在室内接种条件下可以通过体细胞重组产生新小种而导致毒性变异。

The goal of this study was to detect the direct evidence of somatic recombination of Puccinia striiformis through development and characterization experimental isolates using virulence tests and molecular markers under controlled greenhouse conditions. A total of nine pairwise combinations involving seven isolates of P. striiformis fo sp. tritici （wheat stripe rust） and two isolates of P. striiformis f. sp. hordei （barley stripe rust） were selected for this study. ＂Parental＂ and selected variant ＂progeny＂ isolates were tested for virulence patterns on the seedlings of wheat and barley differential cultivars. Eighty-four progeny isolates with virulence patterns were different from the parental isolates. The results preliminarily indicated that somatic recombination might occur in rust fungi. Simple sequence repeat （SSR） markers were used to identify somatic recombinant isolates. A total of 28 progeny isolates from the five pairwise combinations were tested by 6 of 11 SSR markers Three isolates had SSR patterns being different from their ＂parental＂ isolates and the combined bands from both parenta solates, indicating that the three isolates were recombinants. The three isolates were also determined as recombinants in the virulence tests. The results demonstrate that somatic recombination is a mechanism by which new variants can be generated in P. striiformis and lead to virulence variation