Intron retention and down-expression of defense response-related genes together affect the susceptibility of mutants pls4 to rice sheath bligh

Pls4 is a gene encoding a β -ketoacyl carrier protein reductase (KAR), which is mainly involved in biological processes such as cell membrane formation. However，the role of pls4 in rice sheath blight remains unclear. Our preliminary studies showed that rice pls4 mutants were highly susceptive to sheath blight in early development stage, and insensitive in adulthood. To explore the role of this gene in the occurrence of rice sheath blight, we compared the transcriptome profiles of rice pls4 mutant and wild-type by RNA-seq. The results showed that, 2569 differentially expressed genes (DEGs), and down-regulated genes were significantly enriched in defense response related biological stress. The expression pattern significantly changed in genes related to pattern-triggered immunity (PTI) and effector-triggered immunity (ETI), which were the main two innate immunity pathways in plants. The chitinase-related genes were mainly down-regulated, while both the disease-related genes and the related genes of the WRKY gene family were significantly up-regulated. Furthermore, 467 genes had significantly alternative splicing (AS) events. Among them, intron retention (IR) affected the gene expression levels and functions in vitamin B6 (VB6) metabolism pathway, which was related to sheath blight. This suggested that IR played an important role in sheath blight resistance of mutant pls4. In conclusion, these studies suggested that pls4 might be involved in the biological stress process of sheath blight by DEGs and the fine-tuning of IR, which would provide a molecular basis for the study of rice sheath blight resistance. Comparative gene expression profiling analysis of RNA-seq data for wild type and pls4 mutant.