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Lesion-mimic mutants (LMMs) serve as valuable resources for uncovering the molecular mechanisms that govern programmed cell death (PCD) in plants. Despite extensive research, the regulatory mechanisms of PCD and lesion formation in various LMMs remain to be fully elucidated. In this study, we identified a rice LMM named early leaf lesion and senescence 1 (els1), cloned the causal gene through map-based cloning, and confirmed its function through complementation. ELS1 encodes an anthranilate synthase α-subunit involved in anthranilate biosynthesis. It is predominantly localized in chloroplasts and is primarily expressed in light-exposed tissues. Mutation of ELS1 triggers upregulation of its homologous gene, ASA1, via a genetic compensation response, leading to the activation of the tryptophan (Trp) synthesis pathway and amino acid metabolism. The accumulation of abnormal Trp-derived intermediate metabolites results in reactive oxygen species (ROS) production and abnormal PCD in the els1 mutant, ultimately causing the leaf lesion phenotype. The els1 mutant also exhibits reduced chlorophyll content, upregulation of genes related to chloroplast degradation and leaf senescence, and decreased activity of photosynthetic proteins, indicating that ELS1 plays a role in chloroplast development. These factors collectively contribute to the premature leaf senescence observed in the els1 mutant. Our findings shed light on the role of ELS1 in regulating ROS accumulation and PCD in rice, providing further genetic insights into the molecular mechanisms governing leaf lesions and senescence., (© 2024 Society for Experimental Biology and John Wiley & Sons Ltd.)

Rice ( Oryza sativa L.) is a major food crop and increasing rice yield is the primary objective of rice research. Photosynthesis and nitrogen utilization efficiency directly affect the tiller number of rice, which affects the yield of rice. In this study, a stable yellow leaf and less tillering rice mutant yllt10 ( yellow leaf and less tillering 10 ) was obtained by heavy-ion beam mutagenesis of rice variety 'Ke-fu-geng 7'. Compared with the wild type, yllt10 showed reduced chlorophyll content, decreased photosynthesis rate, and abnormal chloroplast structure. The genetic analysis indicated that the phenotype of yllt10 was controlled by a single recessive nuclear gene. Map-based cloning localized YLLT10 between two molecular markers J4 and J5 on chromosome 10. The sequencing of candidate genes within this interval revealed that YLLT10 was an allelic mutation of CAO1/PGL with a single base deletion in the first exon resulting in the frame shift mutation of CAO1/PGL , and YLLT10 was a new allelic variation of CAO1/PGL . The mutant yllt10 was insensitive to changes in nitrogen concentration when being incubated with different nitrogen concentrations. YLLT10 controls leaf color and tiller number and affects photosynthesis and yield of rice. The study of this gene provides a theoretical basis for molecular breeding of rice.