Gene transcription is governed by a complex regulatory system involving changes in chromatin structure, action of transcription factors, and activation of cis-regulatory elements. Postharvest fruits are threatened by Penicillium expansum, a leading causal agent of blue mold disease and one of the most economically significant postharvest pathogens worldwide. However, the information on its transcription regulatory mechanism is lagging. Here, we conducted an assay for transposase accessible chromatin sequencing (ATAC-seq) for P. expansum during vegetative growth and infection phase and then studied the function of a bZIP transcription factor PeAtf1. Results highlighted the role of promoter regions in gene transcription and the significant difference in P. expansum between the two phases. Six footprint-supported cis-regulatory elements of active transcription factors were obtained and analyzed. We then identified a homolog of the bZIP regulator Atf1, PeAtf1, and found it positively regulated vegetative growth, reproduction and osmotic stress response in P. expansum. Conversely, PeAtf1 deletion enhanced fungal tolerance to oxidative, cell wall and membrane stresses, which might contribute to the virulence of P. expansum in apple fruits, leading to similar pathogenicity between mutants and the wild type. Overall, this study provides new insights into the transcription regulatory mechanism of P. expansum, aiding in the future development of strategies to control P. expansum.

中文翻译：

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染色质可及性谱和 PeAtf1 转录因子在采后病原体 Penicillium expansum 中的作用


基因转录受到复杂的调控系统的控制，涉及染色质结构的变化、转录因子的作用以及顺式调控元件的激活。采后水果受到扩展青霉菌的威胁，它是蓝霉病的主要致病菌，也是全球最具经济意义的采后病原体之一。然而，关于其转录调控机制的信息却滞后。在这里，我们对 P. expansum 在营养生长和感染阶段进行了转座酶可及染色质测序 (ATAC-seq) 分析，然后研究了 bZIP 转录因子 PeAtf1 的功能。结果强调了启动子区域在基因转录中的作用以及两个阶段之间 P. expansum 的显着差异。获得并分析了六个足迹支持的活性转录因子顺式调控元件。然后，我们鉴定了 bZIP 调节因子 Atf1 的同源物 PeAtf1，并发现它对 P. expansum 的营养生长、繁殖和渗透胁迫反应具有正向调节作用。相反，PeAtf1 缺失增强了真菌对氧化、细胞壁和膜应激的耐受性，这可能有助于苹果果实中 P. expansum 的毒力，导致突变体和野生型之间具有相似的致病性。总的来说，这项研究为 P. expansum 的转录调控机制提供了新的见解，有助于未来开发控制 P. expansum 的策略。