叶绿体基因编码蛋白质在水稻叶片生长过程中的表达研究

叶绿体是绿色植物把光能转化为化学能的重要细胞器.目前,多种植物的叶绿体基因组序列已经获得,对叶绿体内发生的各种生物学过程人们也已经有相当深入的了解,但对叶绿体基因编码蛋白质的表达还所知甚少.用蛋白质印迹实验系统地检测了15个叶绿体基因编码蛋白质在水稻叶片不同生长时期的表达.其中7个与光合作用相关蛋白质的表达具有相似的模式,其表达量随叶片生长而增加,一般在孕穗期、开花期达到最高峰,在成熟期叶片下降,这种模式与水稻生长对光合作用的需求有明显相关性.4个与DNA复制相关的RNA聚合酶在苗期叶片中表达量达到最高,说明这些聚合酶在较早时期发挥作用.4个NADH脱氢酶蛋白质的表达呈2种不同的模式,其中亚基2和4在种子萌发后的早期叶片中就达到最高峰,亚基5和7的最高峰出现在中后期,反映了它们之间功能上的不同.实验结果直观且相对定量地揭示了叶绿体编码蛋白质的表达与叶片生长之间的关联关系,为深入了解其功能提供了重要的线索.

Expression profiling of chloroplast-encoded proteins in rice leaves at different growth stages

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.