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

Abstract

Controlled hybridization of commercial apple cultivars was carried out from 1973 to 1979. Fruit coloring potential was evaluated in F1 progeny during 1989–1992 and biochemical analyses of F1 fruit were conducted in 1993. Crosses between red-fruited cultivars produced less colored progeny, while hybridization of non-red fruited cultivars yielded a high frequency of red fruited F1 trees. Anthocyanin concentration in commercial cultivars and their F1 progeny paralleled UDPGalactose: flavonoid-3- o-glycosyltransferase (UFGalT) activity, but did not correlate with phenylalanine ammonia-lyase (PAL) and chalcone synthase (CS) activity. When harvest was delayed and light intensity increased, both green (`Indo' and `White Winter Pearmain') and yellow (`Golden Delicious' and `Guoshuai') fruited cultivars accumulated a certain amount of anthocyanin, resulting red area with higher UFGalT activity in fruit peel. In cultivars or F1 progeny with striped fruit, the red area contained 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 trees and their progeny. However, relatively high UFGalT activity was also detected in fruit peel of non-red fruited cultivars, and in fruit peel of red-fruited cultivars without red color development. These results indicate that UFGalT is one of the key enzymes in regulating anthocyanin synthesis during fruit maturation, but PAL and CS are not.