Transcriptional Activation And Metabolic Regulation Of Flavonoid Pathway In Blueberries By Ultraviolet Irradiation

This experiment was based on the changes between the content of flavonoids, the activities of biosynthetic enzymes and genes expression in blueberry during the development, which aimed at further testing accumulations of flavonoids in blueberry and the enzyme activities, transcriptional level of flavonoids biosynthetic gene under the environmental stimulus of preharvest and postharvest UV radiation with different developmental stages fruit of "Northland" Blueberry. The major findings are listed as following:1. During the developmental of blueberry,the accumulation of anthocyanin and flavonoid in the early stage of fruit development, the synthesis of anthocyanin in the late stage of fruit development, and these changes are consistent with the corresponding regulatory genes and structural gene changes. At the same time, the synthesis of anthocyanin was closely related to the content of fructose and glucose, and the PA and flavonoids were significantly correlated with the antioxidant capacity of fruit.2. Different doses of three kinds of UV irradiation in detached blueberry fruit, in young fruit, flavonoids content and enzyme activity increased with the increase of UV-A irradiation dose, and decreased with UV-B and UV-C irradiation dose increased. and UV-A induced effect is obviously better than that of UV-B and UV-C. After UV-B and UV-C irradiation, the activation effect of flavonoid pathway in white fruit was significantly higher than that of UV-A. and increase with the increase of irradiation dose, hi attached UV treatment, with the increase of UV-B and UV-C irradiation dose, fruit total phenolics and proanthocyanidins content presenting increasing trend.3. Detached and attached UV irradiation differently induced the flavonoid pathway gene structure and regulation of gene transcription expression, they have distinct developmental phases correlation and UV wavelength correlation.In the early stage of fruit development, detached UV irradiation mainly induced promotion of flavonol content in fruit developmental stage, and at the late stage of fruit development mainly induced anthocyanin accumulation, UV-C had the most obvious induction effect. And attached UV irradiation mainly induced the accumulation of PAs and flavonols in the early stage of fruit development, at the late stage of fruit late development mainly induced the synthesis of anthocyanin, which UV-B induced effect is more obvious than that of UV-C.4. UV irradiation had different response patterns between detached and attached fruits. First, in detached UV treatment, the effect of the flavonoid pathway was increasing with the decreasing of UV wavelength; But in attached treatment, the activation effect of UV-B was significantly more than that of UV-C. Second, as to dettached fruits, living plants has made system reaction to UV treantment. In detached UV treatment, the PA synthesis turn into flanovol synthesis before veraison by UV induction. After veraison, the sugar and flavonol content decreased and turn to synthesis of anthocyanin; But in attached UV treatment, the synthesis of sugar and flavonoids during whole fruit development stage were activated by UV irradiation. Last, the effect of UV exposure on the flavonoid pathway in attached plants was relatively mild to detached fruits.5. UV irradiation differently induced the increasing of the antioxidant capacity in detached blueberry fruits, and the induction by UV radiation highly depended on the developmental stage of the blueberries and depended on the ultraviolet wavelength. With the increase of fruit maturity, the antioxidant capacity of fruit was more induced. The induction of UV-C was more obvious. Compared to detached UV treatment, attached UV irradiation had little effect on the antioxidant capacity of fruit, and UV-B had a little degree of activation on the antioxidant capacity of the fruit before veraison.