Abstract:

This experiment was carried out to study the relationships among glucose-6-phosphate dehydrogenase (G6PDH), phenylalanine ammonia-lyase (PAL) activity and the concentrations of anthocyanin, by using fruit with bagging and DHEA treatment. Fruits from nine-year-older peach trees (Prunus persica L. Batsch cv ‘zaoyu’) were used as materials in this study. Fruits were bagged at the pit-hardening stage (with removed and without), non-bagged were used as control. And the concentration of anthocyanin, the activities of PAL and G6PDH, subcellular localization of G6PDH were observed. Also, with DHEA treatment, the color of fruit, the activities of G6PDH and anthocyanins were checked. The changes of anthocyanins and the activities of PAL and G6PDH in non-bagged fruit presented similar patterns. The activity and amount of G6PDH in bagged fruits reached a peak under sunlight irradiation, and at the same time the anthocyanin accumulation increased rapidly, but the G6PDH remained active and constant in fruits with bags all through, whereas no anthocyanin produced. By EM immunogold localization, G6PDH resided in cytoplasm and plastids (named chloroplast at an early stage of fruit growth when fruits were green and named chromoplast at the beginning of coloring), the chloroplasts were gracile and procreated by cleavage in bagged fruits. The amount of immunogold particles was coincident with the changes of G6PDH activities. DHEA could inhibit the activity of G6PDH in peach fruit, and which caused a decrease in anthocyanin production. The G6PDH was one of key enzymes controlling anthocyanin biosynthesis.