Expression Profiling of Chloroplast-encoded Proteins in Rice Leaves at Different Growth Stages*

Abstract

Chloroplast is the critical organelle for transforming light energy into chemical energy in plant.At present the whole genome sequences of chloroplast of many plants have been released and the knowledge about biological processes in chloroplast has been accumulated.However,limited information regarding the expression of chloroplast-encoded proteins is available.Fifteen chloroplast genes were selected from chloroplast-encoded proteins and the expression profiling in different stages of rice leaves were investigated by Western blotting.The results indicated that the expression patterns of 7 photosynthesis-related proteins are similar and the expression level increase steadily as leaves grow taller.Until the booting and flowering stages,the expression reached the highest-level,and then decreased at filling stage.The correlation between the expression of photosynthesis-related proteins and the photosynthesis was observed.The expression levels of 4 RNA polymerase related to DNA replication were at their highest-level at seedling stage,which indicated that they perform their functions during the early stage.However,4 NADH dehydrogenase exhibited two kinds of expression patterns.Subunit-2 and-4 reached their highest-level when the leaves were 1cm in length during seedling stage.While,subunit-5 and-7 reached theirs in middle and later stage of seedling.The results implied their different functions during seedling stages.Taking together,this experiment revealed the expression patterns of rice chloroplast-encoded proteins in rice leaves at different growth stages and the correlation between the proteins and the growing process in a direct and relative quantitative way,and provided significant information for further research of their function.