Transcriptome analysis of rice leaves in response to Rhizoctonia solani infection and reveals a novel regulatory mechanism

Sheath blight disease (ShB) severely affects rice production; however, the details of defense against ShB remain unclear. To understand the rice defense mechanism against ShB, an RNA sequencing analysis was performed using Rhizoctonia solani inoculated rice leaves after 48 h of inoculation. Among them, 3417 genes were upregulated and 2532 were downregulated when compared with the control group (> twofold or < 1/2). In addition, the differentially expressed genes were classified via Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and MapMan analyses. Fifty-nine GO terms and seven KEGG pathways were significantly enriched. A MapMan analysis demonstrated that the phytohormone and metabolic pathways were significantly altered. Interestingly, the expression levels of 359 transcription factors, including WRKY, MYB, and NAC family members, as well as 239 transporter genes, including ABC, MFS, and SWEET, were significantly changed in response to R. solani AG1-IA inoculation. Additionally, OsWRKY53 and OsAKT1 negatively regulate the defense response in rice against R. solani via gain of function study for OsWRKY53 and loss of function study for OsAKT1, respectively. Furthermore, several differentially expressed genes contain R. solani-responsive cis acting regulatory elements in their promoter regions. Taken together, our analyses provide valuable information for the additional study of the defense mechanisms against ShB, and the candidate genes identified in this study will be useful resource for future breeding to enhance resistance against ShB.