Transcriptome Analysis Based on Lr19-Virulent Mutants Strain Provides Clues for the Pathogenicity-Related Genes and Effectors of Puccinia Triticina

Background: Wheat leaf rust caused by Puccinia triticina ( Pt ) remains one of the most destructive diseases of common wheat worldwide. Cultivating resistant cultivars is an effective way to control this disease, but race-specific resistance can be overcome quickly due to the rapid evolution of Pt populations. The critical to control wheat leaf rust is to understand the pathogenicity mechanisms of Pt . Results: : In this study, the spores of the Pt race PHNT (wheat leaf rust resistance gene Lr19 -avirulent isolate) were mutagenized with ethyl methanesulfonate (EMS) and two Pt Lr19 -virulent mutants named M1 and M2 were isolated, suggesting that they carry mutations affecting the Lr19 -specific avirulent factor. RNA sequencing was performed on samples collected from the wheat cultivars Chinese Spring and TcLr19 that were infected by wild-type (WT) PHNT and the two Lr19 -virulent mutant isolates at 14 days post-inoculation (dpi). The assembled transcriptome data were compared to the reference genome “ Pt 1-1 BBBD Race 1.” A total of 216 differentially expressed genes (DEGs) were found from three different sample comparisons including M1-vs-WT, M2-vs-WT, and M1-vs-M2. Of these DEGs, 29 common DEGs were shared between M1-vs-WT and M2-vs-WT comparisons. Among the 216 DEGs encoding proteins, 30 were predicted to be effector candidates. Then 6 effector candidates (PTTG_27844, PTTG_05290, PTTG_27401, PTTG_27224, PTTG_26282, PTTG_25521) were verified that these genes were differentially expressed during Pt infection by quantitative real-time PCR (qRT-PCR) and were validated on tobacco, and the results showed that PTTG_27401 could inhibit progress of cell death (PCD) induced by BAX. Conclusions: : Our results showed that a large number of genes participate in the interaction between Pt and TcLr19, which will provide valuable resources for the identification and targeting of AvrLr19 effector candidates and pathogenesis-related genes. Furthermore, our analyses are of great significance to reveal the pathogenesis of Pt .