Abstract: Content of anthocyanin and the activities of enzymes in anthocyanin biosyntheses including plenylalanine ammonia lyase (PAL), chalcone ismoerase (CHI), dihydroflavonol reductase (DFR) and UDP glucose-flavonoid-3-o-glycosyltranfe-rase (UFGT) were investigated using Padus virginiana 'Schubert' in the leaf color-changing period, and P.resemosa was taken as control. The results indicated that from May to July the content of anthocyanin in the leaves at the base, middle and top of branches in P.virginiana 'Schubert' increased by 219.40%, 666.63% and 76.81%. The activity of PAL was quadratically correlated with the content of anthocyanin, and the content of anthocyanin increased as the PAL activity increased after it was higher than 60 U·g^-1 FW. CHI activity was significantly and positively correlated with the content of anthocyanin. The content of anthocyanin increased also with an increase in DFR activity when it was between 50 and 150 U·g^-1 FW. There was a power function correlation between UFGT activity and content of anthocyanin, and the increase in UFGT activity could significantly raise the content of anthocyanin.

Key words: Padus virginiana 'Schubert', anthocyanin, enzyme activity