SummarySouthern corn rust (SCR), caused by Puccinia polysora Underw (P. polysora), is a catastrophic disease affecting maize, leading to significant global yield losses. The disease manifests primarily as pustules on the upper surface of corn leaves, obscuring our understanding of its cellular heterogeneity, the maize's response to its infection and the underlying gene expression regulatory mechanisms. In this study, we dissected the heterogeneity of maize's response to P. polysora infection using single‐cell RNA sequencing. We delineated cell‐type‐specific gene expression alterations in six leaf cell types, creating the inaugural single‐cell atlas of a maize leaf under fungal assault. Crucially, by reconstructing cellular trajectories in susceptible line N110 and resistant line R99 during infection, we identified diverse regulatory programs that fortify R99's resistance across different leaf cell types. This research uncovers an immune‐like state in R99 leaves, characterized by the expression of various fungi‐induced genes in the absence of fungal infection, particularly in guard and epidermal cells. Our findings also highlight the role of the fungi‐induced glycoside hydrolase family 18 chitinase 7 protein (ZmChit7) in conferring resistance to P. polysora. Collectively, our results shed light on the mechanisms of maize resistance to fungal pathogens through comparative single‐cell transcriptomics, offering a valuable resource for pinpointing novel genes that bolster resistance to P. polysora.

中文翻译：

---

玉米细胞异质性和针对 Puccinia polysora Underw 的全身免疫反应的单细胞转录组学分析


摘要由多叶锈菌 （P. polysora） 引起的南方玉米锈病 （SCR） 是一种影响玉米的灾难性病害，导致全球产量的重大损失。该病害主要表现为玉米叶片上表面的脓疱，掩盖了我们对玉米细胞异质性、玉米对其感染的反应以及潜在的基因表达调节机制的理解。在这项研究中，我们使用单细胞 RNA 测序剖析了玉米对 P. polysora 感染反应的异质性。我们描绘了六种叶细胞类型的细胞类型特异性基因表达改变，创建了真菌攻击下玉米叶的首个单细胞图谱。至关重要的是，通过在感染过程中重建易感细胞系 N110 和耐药细胞系 R99 中的细胞轨迹，我们确定了增强 R99 在不同叶细胞类型中的耐药性的不同调节程序。这项研究揭示了 R99 叶片中的免疫样状态，其特征是在没有真菌感染的情况下表达各种真菌诱导的基因，特别是在保卫细胞和表皮细胞中。我们的研究结果还强调了真菌诱导的糖苷水解酶家族 18 几丁质酶 7 蛋白 （ZmChit7） 在赋予对 P. polysora 的抗性中的作用。总的来说，我们的结果通过比较单细胞转录组学阐明了玉米对真菌病原体的抗性机制，为确定增强对 P. polysora 的抗性的新基因提供了宝贵的资源。