Abstract rbcL is the gene which codes the large subunit of the photosynthetic enzyme, Rubisco. Its EST sequence, whose expression is inhibited by the enhanced UV-B radiation, was obtained from the leaf cDNA of alpine plant Elymus sibiricus L. cv. 'chuancao No.2' by reverse transcription-polymerase chain reaction (RT-PCR) differential display method and a 1.51 kb full-length cDNA was cloned through 5' RACE. The rbcL has a 1.434 kb open reading frame (ORF) which encodes a precursor protein of 477 amino acid residues. The amino acid sequence exhibits 97%, 98% and 98% positional identity with its correspondent from Elymus trachycaulus、Triticum aestivum、Hordeum comosum, respectively. Northern hybridization analysis on the rbcL expression during the time of enhanced UV-B radiation, showed that the mRNA level of the rbcL descended obviously after being exposed to enhanced UV-B radiation for 6h, and 60h later, the mRNA even couldn't be detected. 'chuancao No.2' Growing in the plateau area for a long time and being radiated strongly by the UV-B, the rbcL transcription of Elymus sibiricus L might be restrained like the plain plants, which are sensitive to UV-B.
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