Pyricularia oryzae, a blast fungus of gramineous plants, is composed of various host genus-specific pathotypes. The avirulence of an Avena isolate on wheat is conditioned by PWT3 and PWT4. We isolated the third avirulence gene from the Avena isolate and designated it as PWT7. PWT7 was effective as an avirulence gene only at the seedling stage or on leaves. PWT7 homologs were widely distributed in a subpopulation of the Eleusine pathotype and the Lolium pathotype but completely absent in the Triticum pathotype (the wheat blast fungus). The PWT7 homolog found in the Eleusine pathotype was one of the five genes involved in its avirulence on wheat. A comparative analysis of distribution of PWT7 and the other two genes previously identified in the Eleusine pathotype suggested that, in the course of parasitic specialization toward the wheat blast fungus, a common ancestor of the Eleusine, Lolium, Avena, and Triticum pathotypes first lost PWT6, secondly PWT7, and, finally, the function of PWT3. PWT7 or its homologs were located on core chromosomes in Setaria and Eleusine isolates but on supernumerary chromosomes in Lolium and Avena isolates. This is an example of interchromosomal translocations of effector genes between core and supernumerary chromosomes. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

中文翻译：

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位于多余染色体上的 PWT7 缺失与稻瘟病菌在小麦上的特化寄生有关。

稻瘟病菌是禾本科植物的一种稻瘟病菌，由多种宿主属特异性致病型组成。燕麦分离株对小麦的无毒力是由 PWT3 和 PWT4 决定的。我们从燕麦分离株中分离出第三个无毒基因，并将其命名为 PWT7。PWT7作为无毒基因仅在幼苗期或叶上有效。PWT7 同源物广泛分布在牛筋草致病型和黑麦草致病型的亚群中，但在小麦致病型（麦瘟真菌）中完全不存在。在牛筋草致病型中发现的 PWT7 同源物是涉及其对小麦无毒力的五个基因之一。对 PWT7 和之前在牛筋草致病型中鉴定的其他两个基因分布的比较分析表明，在麦瘟真菌的寄生特化过程中，牛筋草、黑麦草、燕麦和小麦致病型的共同祖先首先失去了 PWT6 ，其次是PWT7，最后是PWT3的功能。PWT7 或其同源物位于狗尾草和牛筋草分离株的核心染色体上，但位于黑麦草和燕麦分离株的多余染色体上。这是效应基因在核心染色体和多余染色体之间染色体间易位的一个例子。[公式：见文字] 版权所有 © 2023 作者。这是一篇根据 CC BY-NC-ND 4.0 国际许可证分发的开放获取文章。