Abstract
Bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is an overwhelming disease in rice-growing regions worldwide. Our previous studies revealed that the executor R gene Xa23 confers broad-spectrum disease resistance to all naturally occurring biotypes of Xoo. In this study, comparative transcriptomic profiling of two near-isogenic lines (NILs), CBB23 (harboring Xa23) and JG30 (without Xa23), before and after infection of the Xoo strain, PXO99A, was done by RNA sequencing, to identify genes associated with the resistance. After high throughput sequencing, 1645 differentially expressed genes (DEGs) were identified between CBB23 and JG30 at different time points. Gene Ontlogy (GO) analysis categorized the DEGs into biological process, molecular function, and cellular component. KEGG analysis categorized the DEGs into different pathways, and phenylpropanoid biosynthesis was the most prominent pathway, followed by biosynthesis of plant hormones, flavonoid biosynthesis, and glycolysis/gluconeogenesis. Further analysis led to the identification of differentially expressed transcription factors (TFs) and different kinase responsive genes in CBB23, than that in JG30. Besides TFs and kinase responsive genes, DEGs related to ethylene, jasmonic acid, and secondary metabolites were also identified in both genotypes after PXO99A infection. The data of DEGs are a precious resource for further clarifying the network of Xa23-mediated resistance.
Highlights
Pathogens cause extensive damage to agriculture and food commodities
We identified several differentially expressed genes (DEGs), including different transcription factors (TFs), kinase responsive genes, and clusters of genes involved in different gene ontology terms (GO) and Kyoto encyclopedia of genes and genomes (KEGG) pathways
Leaves of CBB23 and JG30 genotypes were infected by PXO99A via scissors-clipping method, for the confirmation of resistant and susceptible genotypes (Figure 1A)
Summary
Pathogens cause extensive damage to agriculture and food commodities. According to molecular clocks, land plants evolved 700 million years ago, and the establishment of land plants was facilitated by the symbiotic microbe association [1]. Bacterial blight was first reported by the Japanese farmers in 1884, but not taken seriously due to it causing less damage [6] This disease appeared again drastically in high yielding varieties during 1960–1970 [7]. Because Xa23 confers broad-spectrum resistance against Xoo, it is necessary to conduct an independent study to compare the gene expression profiles of the CBB23 and JG30 rice genotypes during different Xoo infection stages (12, 24, 36, and 48 h of post inoculation (hpi)). We identified several DEGs, including different transcription factors (TFs), kinase responsive genes, and clusters of genes involved in different gene ontology terms (GO) and Kyoto encyclopedia of genes and genomes (KEGG) pathways These DEGs would be a valuable resource for future molecular studies of rice resistance against Xoo infection
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