叶绿体是光合作用以及多种代谢产物合成和积累的主要场所，叶绿体发育受阻将影响植物体的生长，因此，研究叶绿体发育机制具有重要的理论价值和实践意义。本研究利用叶绿体发育受阻突变体asl4，分离一个控制水稻幼苗生长发育基因ASL4，该基因编码一个叶绿体核糖体小亚基蛋白S1。叶绿体核糖体蛋白在叶绿体核糖体的形成、质体蛋白合成及叶绿体分化中行使重要的功能，然而，其分子机理和调控机制尚不清楚。本项目拟综合运用遗传学、基因组学、分子生物学等技术手段明确ASL4基因在质体编码基因表达和蛋白合成过程中行使的功能，探索该基因突变与叶绿体分化和叶绿体核糖体形成之间的关系，筛选PRPS1的互作蛋白，研究该蛋白可能参与的分子生物学途径，以期阐明ASL4基因调控叶绿体发育和植株幼苗生长的分子机理。

Chloroplasts are not only the exclusive place of photosynthesis in higher plants, but they are also responsible for the biosynthesis and storage of various metabolites. Abnormal chloroplast development would affect plant growth. Therefore, it is of great importance to study the mechanism of chloroplast function. The proposer previously isolated a chloroplast development deficient mutant named asl4, and identified the ASL4 gene which encodes the chloroplast ribosomal small subunit protein S1 as an essential regulator required for rice seedling growth. The chloroplast ribosome proteins play important roles in chloroplast ribosome biogenesis, plastid protein biosynthesis and chloroplast differentiation, however, the molecular functions and regulatory mechanisms of which are largely unknown. The project intends to clarify the function of ASL4 gene in expression and synthesis of plastid-encoded genes and proteins by using of genetics, genomics and molecular biology. This study will try to explore the relationship between ASL4 mutation and chloroplast differentiation and chloroplast ribosome biogenesis. The interacted protein of PRPS1 could be identified for exploration of the molecular biological pathways that PRPS1 may participate in. This project will try to elucidate the molecular mechanism of ASL4 that regulates chloroplast development and rice seedling growth.