บทคัดย่องานวิจัย

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Molecular cloning of UDP-glycosyltransferase genes: differential expression patterns during apple fruit ripening

C.Honda , S. Kobayashi , N. Kotoda , M. Kita , T. Tsuda and T. Moriguchi

Proceedings of 26th International Horticultural Congress. Volume of Abstract. Toronto, Canada, 11-17 August, 2002. pp. 259.

2002

บทคัดย่อ

Molecular Cloning of UDP-Glycosyl Transferase Genes : Differential Expression Pattern During Apple Fruit Ripening

Red skin color is an important factor for market acceptance of many apple cultivars (Malus x domestica). Red coloration is determined by anthocyanin levels. The main anthocyanin in apple fruit is cyanindin-3-galactoside, suggesting that a key enzyme genetically controlling red coloration is UDP-galactose:flavonoid-3-0-galactosyltransferase (UFGalT), but not UDP-galactose:flavonoid-3-0-galactosyltransferase (UFGalT), but not UDP-glucose:flavonoid-3-0-glucosyltransferase (UFGlcT). To isolate the UFGalT genes in apple, a cDNA library using mRNAs extracted from ‘Jonathan’ apple skin at the mature stage was constructed. Because of sequence similarity between UFGalT and UFGlcT, the fragment obtained from ‘Jonathan’ that showed high similarity to the UFGlcT gene from ‘Fuji’ (accession number AF 117267) was used as a probe. Five positive clones wee obtained from the 106 pfu by screening the library. All five cDNAs lacked the 5’ ends, and these cDNA clones fell into two groups bsed on the nucleotide sequences. In the first group (one clone), the cDNA showed high similarity to the fragment used as a probe. In the second group (four clones), sequence similarities of the cDNAs to the probe sequence were less pronounced. Northern blot analysis was done using three apple cultivars which differed in skin coloration; a yellow skin type ‘Orin’ and red skin types ‘ Jonathan’ and ‘Fuji’. The expression of the clone from the first group increased only in the red skin types during fruit maturation, indicating the correlation wity anthocyanin accumulation. On the other hand, expression levels of clones from the seceond group were quite low in immature fruit and increased during ripening in both skin color types. These results suggested that the two groups of the UDP-glycosyltransferase genes were differentially regulated during fruit ripening. To better understand the mechanisms of anthocyanin accumulation in aple fruit, an experiment to isolate the full-legth genes encoding UFGalT is in progress.