rbcL是编码光合关键酶1,5-二磷酸核酮糖羧化酶（Rubisco）大亚基的基因。本文运用mRNA差异显示技术（DDRT-PCR）并通过5ˊRACE (Rapid Amplification of cDNA Ends) 从高原植物川草2号老芒麦（Elymus sibiricus L. cv. 'chuancao No.2'）中获得了受增强UV-B辐射抑制的rbcL基因，该基因全长cDNA为1.51kb，开放阅读框（ORF）长1.434kb，编码477个氨基酸。氨基酸序列与Elymus trachycaulus中的Rubisco大亚基具有97％的同源性、与Triticum aestivum和Hordeum comosum的Rubisco大亚基同源性均为 98％。Northern杂交分析表明，增强UV-B辐射后6h，rbcL基因表达受到强烈抑制，处理后60h，其表达几乎完全被抑制，表明即使是长期生长在高原地区、强UV-B辐射条件下的高原物种，在受到较强的UV-B辐射后，其rbcL基因的转录也会受到抑制。

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.