This study was conducted on the lesion-mimic mutant lm5, which was produced by mutagenesis of WYJ21 (WT) using ethyl methane sulfonate (EMS). The mutant lm5 was short in the seedling stage and displayed yellowish-brown disease-like spots on leaves that were yellowish-brown when the plant was at the tillering stage. The disease-like spots gradually grew larger as the plant grew until it reached maturity. Compared to WT, lm5 had considerably reduced the plant height, ear panicle length, tiller number, and 1000-grain weight. A single recessive gene was found to be in control of lm5, according to a genetic study. It was physically located 245 kb apart between the RM21160 and RM180 markers on chromosome 7. Using RiceData and other websites, analyze and sequence potential gene candidates. Exon 7 of LOC_Os07g10390 (OsLM5) was identified to have a mutation that changed the 1560 base from G to A, changing the 788 amino acids from Arg to Lys. The OsLM5 gene was found to be a new allele of the SPL5 gene, encoding the protein shear factor SF3b3. Studies showed that OsLM5 was localized in the nucleus, and OsLM5 was significantly expressed in leaves. Reactive oxygen species (ROS) accumulation occurred in the leaves and roots of mutant lm5, and qPCR results showed abnormal expression of genes related to chloroplast development as well as significantly increased expression of genes related to aging and disease course. The OsLM5 gene may have a significant impact on the regulation of apoptosis in rice cells.
