Objectives: To identify the target gene causes early seedling lethality and preliminary describe the molecular details of L12s function in rice.Methods: A novel rice mutant,albino lethal 1(al1),was obtained.Utilize map-based cloning strategy to isolate the target gene.A series of physiological and biochemical tests were conducted to explore the biology function of AL1.Results: The al1 mutant displayed an albino phenotype at the seedling stage and did not survive past the three-leaf stage.No other apparent differences in plant morphology were observed in the al1 mutant.The albino phenotype of the al1 mutant was associated with decreased chlorophyll content and abnormal chloroplast morphology.Using fine mapping,AL1 was shown to encode the PRPL12,a protein localized in the chloroplasts of rice,and a spontaneous single-nucleotide mutation(C/T),resulting in a residue substitution from leucine in AL1 to phenylalanine in al1,was found to be responsible for the early seedling lethality.This point mutation is located at the L10 interface feature of the L12/AL1 protein.Yeast two-hybrid analysis showed that there was no physical interaction between al1 and PRPL10.In addition,the mutation had little effect on the transcript abundance of al1,but had a remarkable effect on the protein abundance of al1 and transcript abundance of chloroplast biogenesis-related and photosynthesis-related genes.Conclusion: AL1 encodes the PRPL12.A spontaneous single-nucleotide mutation located at the L10 interface feature results in defective physical interaction with L10.Therefore it produces chloroplast developmental defect and early seedling lethality.This study provide a first glimpse into the molecular details of L12s function in rice.