Abstract: A full length cDNA encoding GDP-L-galactose pyrophosphatase（GGP），a key enzyme in the putative L-ascorbic acid（AsA）biosynthetic pathway of higher plants，was obtained from Rosa roxburghii Tratt fruits using RT-PCR and RACE technology. This cDNA，designated RrGGP（accession number，HM998753），contained an open reading frame（ORF）of 1 341 bp，encoding a protein of 445 amino acids. Sequence analysis indicated that its deduced amino acid showed over 80% identities with the corresponding proteins from other plant species. Semi-quantitative RT-PCR showed that the expression of RrGGP in fruits was significantly abundant than that of in leaves，flowers or stems，respectively，contributing to parallel accumulation of AsA. Transcript abundance of RrGGP in developing fruits showed a development-specific profile，in which RrGGP transcript levels were lower in young（10–50 days after anthesis，DAA）and nearly ripe（110–120 DAA）fruits，and higher in fruit in mid-development（60–100 DAA）. This expression pattern showed a well correlation with AsA level，suggesting an important role of this gene in regulating AsA biosynthesis in the fruits.

Key words: Rosa roxburghii, GGP, gene expression, ascorbic acid