Provincial Key Laboratory of Plant Breeding and Genetics, College of Agronomy, Sichuan Agricultural University, Chengdu, Sichuan, China.
PLoS One. 2018 Jul 5;13(7):e0198891. doi: 10.1371/journal.pone.0198891. eCollection 2018.
Blumeria graminis f. sp. tritici (Bgt) is an obligate biotrophic fungus that causes wheat powdery mildew, which is a devastating disease in wheat. However, little is known about the pathogenesis of this fungus, and differences in the pathogenesis of the same pathogen at various resistance levels in hosts have not been determined. In the present study, leaf tissues of both Pm40-expressing hexaploid wheat line L658 and its Pm40-deficient sister line L958 were harvested at 0 (without inoculation), 6, 12, 24, 48 and 72 hours post-inoculation (hpi) with Bgt race 15 and then subjected to RNA sequencing (RNA-seq). In addition, we also observed changes in fungal growth morphology at the aforementioned time points. There was a high correlation between percentage of reads mapped to the Bgt reference genome and biomass of the fungus within the leaf tissue during the growth process. The percentage of mapped reads of Bgt in compatible interactions was significantly higher (at the p<0.05 level) than that of reads in incompatible interactions from 24 to 72 hpi. Further functional annotations indicated that expression levels of genes encoding H+-transporting ATPase, putative secreted effector proteins (PSEPs) and heat shock proteins (HSPs) were significantly up-regulated in compatible interactions compared with these levels in incompatible interactions, particularly at 72 hpi. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis suggested that genes involved in the endocytosis pathway were also enriched in compatible interactions. Overall, genes encoding H+-transporting ATPase, PSEPs and HSPs possibly played crucial roles in successfully establishing the pathogenesis of compatible interactions during late stages of inoculation. The study results also indicated that endocytosis is likely to play a potential role in Bgt in establishing compatible interactions.
禾布氏白粉菌（Blumeria graminis f. sp. tritici，Bgt）是一种专性活体营养真菌，可引起小麦白粉病，这是一种严重危害小麦的疾病。然而，人们对这种真菌的发病机制知之甚少，也没有确定同一病原体在宿主不同抗性水平下的发病机制差异。在本研究中，用 Bgt 小种 15 分别接种表达 Pm40 的六倍体小麦 L658 及其 Pm40 缺失的姊妹系 L958，在接种后 0（未接种）、6、12、24、48 和 72 小时（hpi）收获叶片组织，并进行 RNA 测序（RNA-seq）。此外，我们还观察了上述时间点真菌生长形态的变化。在生长过程中，Bgt 参考基因组映射读段的百分比与叶片组织中真菌的生物量之间存在高度相关性。在 24 至 72 hpi 期间，相容互作中 Bgt 的映射读段百分比显著高于不相容互作（p<0.05）。进一步的功能注释表明，在相容互作中，编码 H+-转运 ATP 酶、假定分泌效应蛋白（PSEP）和热休克蛋白（HSP）的基因表达水平明显高于不相容互作，特别是在 72 hpi 时。此外，京都基因与基因组百科全书（KEGG）途径分析表明，参与内吞作用途径的基因在相容互作中也得到了富集。总的来说，编码 H+-转运 ATP 酶、PSEP 和 HSP 的基因可能在接种后期成功建立相容互作的发病机制中发挥了关键作用。研究结果还表明，内吞作用可能在 Bgt 建立相容互作中发挥了潜在作用。
