Mutation in maize chloroplastic polypeptide chain release factor (ZmcpRF1) affects chloroplast development and leaf color.

Main conclusion: This study identifies the chloroplastic polypeptide chain release factor ZmcpRF1 as a key regulator of chloroplast development and leaf color in maize, affecting both plant survival and growth. Leaf color mutations are a visible phenotype in plants and provide valuable insights into photosynthesis and other biological processes. In this study, we focused on a maize mutant with the segregation of pale green and stunted phenotypes. Genetic analysis showed that these traits were controlled by two independent recessive genes. Using bulked segregant analysis (BSA) and whole-genome sequencing (WGS), three candidate genes were identified for the stunted trait. For the pale green trait, Zm00001eb165700 (chloroplastic polypeptide chain release factor 1, ZmcpRF1) was identified as the only candidate, harboring a missense mutation (c.836G > A|p.G279E). Allelic validation of ZmcpRF1 using another maize mutant with a stop-gain mutation (showing an albino phenotype) further supported this association. The pale green mutant exhibited decreased chlorophyll content, increased relative conductivity (REC), and abnormal chloroplast morphology as compared to normal green plants. This mutant began to wilt at the three-leaf stage and died rapidly by the four-leaf stage. Expression analysis revealed that ZmcpRF1 is predominantly expressed in leaves and is subcellularly localized to chloroplasts. In addition, a conservation analysis was conducted for ZmcpRF1, highlighting its functional importance. These findings underscore the important role of ZmcpRF1 in maize leaf color, chloroplast development, and plant survival.