A Study of the Relationship Between Anthocyanin Biosynthesis and Related Enzymes Activity in Pyrus pyrifolia ‘Mantianhong’ and Its Bud Sports ‘Aoguan’

【Objective】 Study the relationship between anthocyanin biosynthesis and activities of PAL, CHI enzymes in Pyrus pyrifolia. 【Method】Changes in the level of anthocyanin and the activities of enzymes of anthocyanin biosynthesis including plenylalanine ammonialyase (PAL), chalcone ismoerase (CHI) were studied in the pericarp of Pyrus pyrifolia ‘Mantianhong’ and ‘Aoguan’ during the pigment formation period. Bagging treatment was also conducted to manipulate anthocyanin synthesis and the activities of related enzymes during the pigment formation period. 【Result】 The results demonstrated that the content of anthocyanin of ‘Aoguan’ was higher than that of ‘Mantianhong’. However, has the similarly changing trend of the content of anthocyanins was found both in ‘Aoguan’ and ‘Mantianhong’, highest amount of anthocyanin of two varieties was found in immature fruit, lowest amount in mature fruit. Meanwhile, similar changing trends of activities of PAL and CHI were also observed in both varieties. The activity of PAL was decreased during the pigment formation period. The activity of PAL of ‘Aoguan’ was lower than that of ‘Mantianhong’. Whereas the activity of CHI was increased as fruit ripened. The activity of CHI of ‘Aoguan’ was higher than that of ‘Mantianhong’. Bagging treatment inhibited the activity of CHI anthocyanin synthesis, whereas debagging enhanced both the activity of CHI and anthocyanin synthesis as well. However, it did not influence the activity of PAL. The activity of CHI and the amount of anthocyanin in ‘Aoguan’ pericarp after removal of bags was higher than that of control. However, debagging had no apparent influence on the activity of PAL. Anthocyanin of ‘Aoguan’ with bagging was decreased towards harvest【.Conclusion】 The content of anthocyanin of Pyrus pyrifolia was increased at the beginning of fruit coloration period, decreased towards fruit harvest. The activity of PAL was not a key enzyme for colouration, while CHI activity was closely related to the synthesis of anthocyanin. Debagging enhanced the activity of CHI and anthocyanin synthesis. Bagging treatment also showed that anthocyanin degradation was not induced only by light. Light appeared to be necessary for anthocyanin synthesis in pears, and also a factor inducing the decrease of colour through degradation of anthocyanin.