关键词: 拟南芥；AtVTC1；5&rsquo, UTR；内含子；增强子

Abstract: AtVTC1 is one of the key enzymes of L-galactose pathway in Arabidopsis thaliana, which is the primary vitamin C (Vc) biosynthesis pathway. It has been reported that AtVTC1 can be regulated both in transcriptional and post-transcriptional levels. This study found that there was an intron in the 5′UTR (5′untranslated region) of AtVTC1, and this 5′UTR ligated with different truncations of upstream promoter to promote high level expression of GUS, by detecting GUS activity in transgenic seedlings. The GUS expression was significantly reduced under the AtVTC1 promoter with the deletion of 5′UTR intron. However, the intron itself could not be able to activate the GUS expression. Generally the introns function as enhancers with specific nucleotide sequences, such as GATCTG motif, which was dispersed throughout the 5′UTR intron of AtVTC1. Some homologous genes of VTC1 in Arabidopsis and rice also have 5′UTR intron. These results suggested that the 5′UTR intron of AtVTC1 function would be as an enhancer in Arabidopsis, which would lay a foundation for further studies on the modulation of Vc biosynthesis on the transcription level.

Key words: Arabidopsis, AtVTC1, 5′UTR, intron, enhancer