Spot blotch, caused by the pathogen Bipolaris sorokiniana, is an important foliar disease of wheat in warm and humid regions worldwide. The fungal virulence factor ToxA interacts with Tsn1 in wheat and leads to a susceptible reaction. ToxA has been found in B. sorokiniana populations of Australia, the USA, and India, and here we report its occurrence in Mexico, based on analysis of a collection of 196 Mexican isolates of B. sorokiniana. The isolates were collected from experimental stations and farmers’ fields in nine states of Mexico, during the period from 1992 to 2017. A PCR assay with the ToxA-specific marker was conducted, and the results revealed the presence of ToxA in 20 isolates (10.2%). Culture filtrate infiltration experiments confirmed that all the 20 isolates were able to induce necrosis reaction on Glenlea, a wheat genotype with Tsn1. This is the first report on the occurrence of ToxA in Mexican B. sorokiniana population, which is key information for breeding wheat for resistance against spot blotch.

中文翻译：

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ToxA 是一种与小麦斑斑病有关的重要毒力因子，存在于墨西哥的 Bipolaris sorokiniana 种群中

由病原菌 Bipolaris sorokiniana 引起的斑点斑病是全球温暖潮湿地区小麦的重要叶面病害。真菌毒力因子 ToxA 与小麦中的 Tsn1 相互作用并导致易感反应。ToxA 已在澳大利亚、美国和印度的 B. sorokiniana 种群中发现，我们在此报告其在墨西哥的发生，基于对 196 份墨西哥 B. sorokiniana 分离株的分析。1992 年至 2017 年期间，从墨西哥九个州的试验站和农民田间收集了这些分离株。使用 ToxA 特异性标记物进行 PCR 检测，结果显示 20 个分离株中存在 ToxA (10.2 %）。培养滤液浸润实验证实，所有20个分离株都能诱导Glenlea（一种具有Tsn1的小麦基因型）的坏死反应。