Comparative transcriptome profiling of Blumeria graminis f. sp. tritici during compatible and incompatible interactions with sister wheat lines carrying and lacking Pm40

Abstract

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.

Highly flexible infection programs in a specialized wheat pathogen

“…This flexibility may be facilitated by the fact that pathogenesis does not involve the formation of complex penetration or feeding structures that require fine‐tuned developmental programs. In powdery mildew which need to form appressoria as well as haustoria to establish host infections, comparative transcriptomics during early pathogenesis identified a comparatively low number of isolate‐specifically expressed genes in two barley powdery mildew strains (Hacquard et al, ) and showed that transcriptional programs are similar even during incompatible infections and interactions with nonhost species (Hacquard et al, ; Hu et al, ).…”

Potential Role of Photosynthesis in the Regulation of Reactive Oxygen Species and Defence Responses to Blumeria graminis f. sp. tritici in Wheat

“…In our previous study, differences in the infection mechanism of Bgt during the interactions with L658 and L958 were determined [ 54 ]. To further clarify the difference in the molecular response mechanisms between L658 and L958, we continued to analyse the RNA-seq data from the plant side.…”

“…The resistant wheat line L658 carrying Pm40 and its susceptible sister line L958 without Pm40 were used for comparative analyses by observations of cytological changes and determinations of physiological and biochemical indices. In addition, RNA-seq was performed for wheat plants after they were inoculated with Bgt , as described previously [ 54 ]. The fungus was a single-spore isolate collected from a field at Wenjiang Farm, Chengdu, Sichuan Province, and propagated weekly on the highly susceptible wheat line CY20.…”

“…RNA sequencing (RNA-seq) is an effective and powerful method for investigating pathogen infection, host defence and plant-pathogen interaction mechanisms. In our previous study, we compared the transcriptome of Bgt during interactions with the Pm40 -expressing wheat line L658 and the Pm40 -deficient sister line L958 to determine the pathogenesis of Bgt [ 54 ]. In this study, we further analysed the sequencing data with a focus on determining the resistance responses of the host from the other standpoint.…”

Mining&nbsp;the&nbsp;Roles&nbsp;of&nbsp;Wheat (Triticum&nbsp;Aestivum)&nbsp;SnRK&nbsp;Gene&nbsp;Family in&nbsp;Biotic&nbsp;and&nbsp;Abiotic&nbsp;Responses

“…The Blumeria graminis f. sp. Tritici (Bgt strain E09) was maintained on susceptible wheat 'MingXian 169' [77]. The 7-day-old seedlings were inoculated with Bgt conidia from 'MingXian 169' seedlings infected 10 days previously.…”