Zymoseptoria tritici, the causal agent of Septoria tritici blotch, is a fungal wheat pathogen that causes significant global yield losses. Within Z. tritici populations, quantitative differences in virulence among different isolates are commonly observed; however, the genetic components that underpin these differences remain elusive. In this study, intraspecific comparative transcriptomic analysis was used to identify candidate genes that contribute to differences in virulence on the wheat cultivar WW2449. This led to the identification of a multicopy gene that was not expressed in the high-virulence isolate when compared to the medium- and low-virulence isolates. Further investigation suggested this gene resides in a 7.9-kb transposon. Subsequent long-read sequencing of the isolates used in the transcriptomic analysis confirmed that this gene did reside in an active Class II transposon, which is composed of four genes named REP9-1 to -4. Silencing and overexpression of REP9-1 in two distinct genetic backgrounds demonstrated that its expression alone reduces the number of pycnidia produced by Z. tritici during infection. The REP9-1 gene identified within a Class II transposon is the first discovery of a gene in a transposable element that influences the virulence of Z. tritici. This discovery adds further complexity to genetic loci that contribute to quantitative virulence in this important pathogen.

中文翻译：

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影响小麦病原体 Zymoseptoria tritici 无性繁殖的转座子的鉴定

Zymoseptoria tritici是小麦斑点病的病原体，是一种小麦真菌病原体，可导致全球产量显着下降。在小麦中在种群中，通常观察到不同分离株之间毒力的数量差异；然而，支撑这些差异的遗传成分仍然难以捉摸。在这项研究中，种内比较转录组学分析用于鉴定导致小麦品种 WW2449 毒力差异的候选基因。这导致鉴定出与中低毒力分离株相比在高毒力分离株中不表达的多拷贝基因。进一步调查表明该基因位于一个 7.9-kb 的转座子中。随后对转录组分析中使用的分离株进行的长读长测序证实该基因确实存在于一个活跃的 II 类转座子中，该转座子由四个名为REP9-1到-4 的基因组成. REP9-1在两种不同的遗传背景中的沉默和过表达表明，仅其表达就减少了由小麦酵母在感染过程中产生的分生孢子的数量。在 II 类转座子内鉴定出的REP9-1基因是在转座因子中首次发现的影响小麦单孢菌毒力的基因。这一发现进一步增加了遗传基因座的复杂性，这些基因座有助于这种重要病原体的定量毒力。