Coloration potential, anthocyanin accumulation, and enzyme activity in fruit of commercial apple cultivars and their F1 progeny

Controlled hybridization of commercial apple cultivars was carried out from 1973 to 1979. Fruit coloring potential was evaluated in Fl progeny during 1989-1992 and biochemical analyses of F1 fruit were conducted in 1993. Cros ses between red-fruited cultivars produced less colored progeny, while hybr idization of non-red fruited cultivars yielded a high frequency of red frui ted F1 trees. Anthocyanin concentration in commercial cultivars and their F l progeny paralleled UDPGalactose: flavonoid-3-o-glycosyltransferase (UFGal T) activity, but did not correlate with phenylalanine ammonia-lyase (PAL) a nd chalcone synthase (CS) activity. When harvest was delayed and light inte nsity increased, both green ('Indo' and 'White Winter Pearmain') and yellow ('Golden Delicious' and 'Guoshuai') fruited cultivars accumulated a certai n amount of anthocyanin, resulting red area with higher UFGalT activity in fruit peel. In cultivars or F1 progeny with striped fruit, the red area con tained more anthocyanin and a higher activity of UFGalT than adjacent areas from the same fruit. Overall, anthocyanin accumulation and UFGalT activity were highly correlated (r(2)=0.87, p=0.0001) in fruit from both parental t rees and their progeny. However, relatively high UFGalT activity was also d etected in fruit peel of non-red fruited cultivars, and in fruit peel of re d-fruited cultivars without red color development. These results indicate t hat UFGalT is one of the key enzymes in regulating anthocyanin synthesis du ring fruit maturation, but PAL and CS are not. (C) 1999 Elsevier Science B. V. All rights reserved.