Mapping And Functional Analysing Of The ASL1Gene Encoding A Plastid Ribasomal Protein In Rice

Leaf color mutants are one of the common mutant types of rice and play an important role in the study of rice functional genomics. In this paper, we report the mapping and functional analysis of a novel albino mutant (asl1), the main results were summarized as follows:a. asll(albino seedling lethality1) exhibits an albino lethal phenotype at the seedling stage. The data shows that the contents of Chi a, Chi b, and Car approached zero in asll mutant plants compared with the wild type, and thus eads to the albino phenotype. In addition, in usll mutants, normal chloroplasts were not observed by TEM and ehloroplast development appeared to cease at the proplastid stage.b. Genetic analysis showed that the phenotype of asl1mutant was controlled by a single recessive gene. Using SSR and InDel molecular markers and3478individuals of F2generation with mutant phenotype derived from the cross of ASL1/asl1and the indica variety Peiai64S, the ASL1was mapped between the molecular markers P4and P6with60kb of physical distance on the long arm of chromosome1in rice.c. Using bioinformatics methods, we determined LOC-Os01g48690encoding plastid ribosomal proteins S20(RPS20) for the candidate gene. And sequencing results show that there is a2-bp deletion in LOC-Os01g48690.d. ASL1showed tissue-specific expression. as it was highly expressed in young seedlings but expressed at much lower levels in other tissues. In addition, ASL1expression was regulated by light.e. A4.03-kb genomic DNA fragment was cloned into the vector pCAMB1A1301. The resultant plasmid was then transformed into asll mutant callus via Agrobaclerium tumefaciens-mediated transformation. Eleven independent transgenie lines were identified and segregation occurred in the seeds of transgcnic plants (T1).f. We constructed the subccllular localization vector, and the results show that the ASL1localizes to the chloroplast.g. The transcript levels of nuclear genes for Chi biosynthesis and ehloroplast development were strongly affected in asll mutants; transcripts of some plastid genes for photosynthesis were undetectable.Our research discovered a novel albino lethal mutant gene ASL1in rice. The results in this study would in favor of the further functions of this gene, and provide a new theoretical basis for the studying on ehloroplast development.