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Abstract Background Xanthomonas oryzae pv. oryzae ( Xoo ) causes bacterial leaf blight, a devastating rice disease. The Xoo -rice interaction, wherein wide ranging host- and pathogen-derived proteins and genes wage molecular arms race, is a research hotspot. Hence, the identification of novel rice-induced Xoo virulence factors and characterization of their roles affecting rice global gene expression profiles will provide an integrated and better understanding of Xoo -rice interactions from the molecular perspective. Results Using comparative proteomics and an in vitro interaction system, we revealed that 5 protein spots from Xoo exhibited significantly different expression patterns (|fold change| > 1.5) at 3, 6, 12 h after susceptible rice leaf extract (RLX) treatment. MALDI-TOF MS analysis and pathogenicity tests showed that 4 host-induced proteins, including phosphohexose mutase, inositol monophosphatase, arginase and septum site-determining protein, affected Xoo virulence. Among them, mutants of two host-induced carbohydrate metabolism enzyme-encoding genes, Δ xanA and Δ imp , elicited enhanced defense responses and nearly abolished Xoo virulence in rice. To decipher rice differentially expressed genes (DEGs) associated with xanA and imp , transcriptomic responses of Δ xanA -treated and Δ imp -treated susceptible rice were compared to those in rice treated with PXO99 A at 1 and 3 dpi. A total of 1521 and 227 DEGs were identified for PXO99 A vs Δ imp at 1 and 3 dpi, while for PXO99 A vs Δ xanA , there were 131 and 106 DEGs, respectively. GO, KEGG and MapMan analyses revealed that the DEGs for PXO99 A vs Δ imp were mainly involved in photosynthesis, signal transduction, transcription, oxidation-reduction, hydrogen peroxide catabolism, ion transport, phenylpropanoid biosynthesis and metabolism of carbohydrates, lipids, amino acids, secondary metabolites, hormones, and nucleotides, while the DEGs from PXO99 A vs Δ xanA were predominantly associated with photosynthesis, signal transduction, oxidation-reduction, phenylpropanoid biosynthesis, cytochrome P450 and metabolism of carbohydrates, lipids, amino acids, secondary metabolites and hormones. Although most pathways were associated with both the Δ imp and Δ xanA treatments, the underlying genes were not the same. Conclusion Our study identified two novel host-induced virulence factors XanA and Imp in Xoo , and revealed their roles in global gene expression in susceptible rice. These results provide valuable insights into the molecular mechanisms of pathogen infection strategies and plant immunity.
Wu et al. (Sat,) studied this question.