Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
Department of Plant Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
J Exp Bot. 2022 Nov 2;73(19):6697-6710. doi: 10.1093/jxb/erac333.
White mold is caused by the fungal pathogen Sclerotinia sclerotiorum and leads to rapid and significant loss in plant yield. Among its many brassicaceous hosts, including Brassica napus (canola) and Arabidopsis, the response of individual tissue layers directly at the site of infection has yet to be explored. Using laser microdissection coupled with RNA sequencing, we profiled the epidermis, mesophyll, and vascular leaf tissue layers of B. napus in response to S. sclerotiorum. High-throughput tissue-specific mRNA sequencing increased the total number of detected transcripts compared with whole-leaf assessments and provided novel insight into the conserved and specific roles of ontogenetically distinct leaf tissue layers in response to infection. When subjected to pathogen infection, the epidermis, mesophyll, and vasculature activate both specific and shared gene sets. Putative defense genes identified through transcription factor network analysis were then screened for susceptibility against necrotrophic, hemi-biotrophic, and biotrophic pathogens. Arabidopsis deficient in PR5-like RECEPTOR KINASE (PR5K) mRNA levels were universally susceptible to all pathogens tested and were further characterized to identify putative interacting partners involved in the PR5K signaling pathway. Together, these data provide insight into the complexity of the plant defense response directly at the site of infection.
白霉病是由真菌病原体核盘菌引起的，会导致植物产量迅速而显著地损失。在包括油菜（油菜）和拟南芥在内的许多十字花科宿主中，感染部位的各个组织层的直接反应尚未得到探索。我们使用激光微切割结合 RNA 测序，对油菜的表皮、叶肉和叶脉组织层对核盘菌的反应进行了分析。与全叶评估相比，高通量的组织特异性 mRNA 测序增加了检测到的转录本总数，并为不同组织层在感染反应中的保守和特定作用提供了新的见解。当受到病原体感染时，表皮、叶肉和脉管系统会激活特异性和共享的基因集。通过转录因子网络分析鉴定的假定防御基因随后被筛选出来，以对抗坏死型、半活体营养型和活体营养型病原体。PR5K mRNA 水平缺乏拟南芥的 PR5K 对所有测试的病原体普遍易感，并进一步进行了特征鉴定，以确定 PR5K 信号通路中涉及的假定相互作用伙伴。这些数据共同深入了解了感染部位直接的植物防御反应的复杂性。
