Comparative Transcriptome Analysis of Rhizoctonia solani-resistant and -Susceptible Rice Cultivars Reveals the Importance of Pathogen Recognition and Active Immune Responses in Host Resistance

Rice sheath blight (SB), caused by Rhizoctonia solani (R. solani), is a major threat to rice production worldwide. The molecular mechanisms of the SB resistance in rice are poorly understood. The transcriptomes of the SBresistant rice cultivar YSBR1 and the susceptible cultivar Lemont were analyzed after R. solani infection. A total of 7624 differentially expressed genes (DEGs) were identified at one or more timepoints in a cultivar. 5526 and 5618 DEGs were differentially expressed in Lemont and YSBR1, respectively. YSBR1 exhibited stronger and earlier transcriptional response to R. solani than Lemont. Gene ontology enrichment analysis revealed that genes that encode cell wall-modifying and glycosyl-degrading enzymes or anti-microbial proteins were specifically induced in YSBR1 at 6 hpi. MapMan analysis revealed that more DEGs related with cell wall, beta-glucanses, respiratory burst, phenylpropanoids and lignin were highly induced by R. solani in YSBR1 than in Lemont. The results also showed that receptor-like kinases and jasmonic acid signaling may play important roles in host resistance to R. solani. This study highlights potential candidate genes and signaling pathways involved in rice sheath resistance and can help to further clarify the mechanistic events underlying resistance and susceptibility to R. solani.