细胞分裂素在mRNA和蛋白质水平上同时促进rbcS基因的表达

将紫萍半叶状体首先在不含细胞分裂素的培养液上于黑暗条件下培养10d，然后转移到长日照条件下、分别在含有或不含6—苄基嘌呤的新鲜培养液上培养．对半叶状体在培养过程中干重、叶绿素和可溶性蛋白含量方面的变化进行了分析，并且用Northern　blot的方法拉测了rbcS mRNA水平的变化，用SDS—PAGE分离和考马氏亮蓝染色的方法检测了其编码蛋白(1，5—二磷酸核酮糖羧化酶／加氧酶的小亚基，SSU)水平的变化．结果表明，6—苄基嘌吟显著地促进了半叶状体干重、叶绿素和可溶性蛋白含量、rbcS基因mRNA及其编码蛋白SSU水平的增加．由于在没有外源细胞分裂素的情况下，rbcS基因mRNA水平的增加并不能引起SSU水平的增加，所以认为细胞分裂素对该基因表达的促进作用同时发生在mRNA和蛋白质水平上．

PROMOTION OF THE EXPRESSION OF rbcS GENE BY CYTOKININ IS ON BOTH THE mRNA AND THE PROTEIN LEVEL

Half-fronds of Spirodela polyrrhiza P143 plants were first cultivated on a medium without cytokinins in the darkness for 10d and then transferred on a fresh medium with or without 6-benzyladenine and cultivated underlong-day conditions. Changes in dry weight, chlorophyll and soluble protein content were analyzed. The mRNA levels of rbcS gene were detected by Northern blot method and its encoding protein (the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase, SSU) levels were detected after SDS-PAGE separation of the soluble protein and stained with Coomassie brilliant blue. Results showed that 6-benzyladenine promotedsignificantly increases in dry weight, chlorophyll and soluble protein contents, both the SSU and the mRNA level of the rbcS gene. As an increase in SSU level was not detected in the absence of exogenous cytokinins in spite of the increase in its mRNA level, it is proposed that cytokinins enhance the expression of rbcS gene on both the mRNA and the protein level.