The Physiological And Biochemical Analysis Of Melon Transformed By Over-Expression, Interference Vectors Of α-Man Gene

Melon (Cucumis melo L. cv. Hetao) has an apparent process of respiratory climacteric. Melon fruits can easily perishable deteriorate after maturity and has short shelf life, which seriously restrict the development of melon industry. Alpha-Mannosidase is one of the exoglycosidase for the formation of N-glycan. The increasing content of free N-glycans are signals of fruit maturity in the process of fruit development and postharvest storage. Current researches show that α-Man gene plays an important role in fruit development.In order to determine the function of α-Man gene in the process of fruit development and postharvest storage. This research took T3 generation melon fruits transformed by over-expression vector (pPZP221-α-Man) and RNAi vectors (pART27-α-Manl and pART27-α-Man2) of α-Man gene as materials for the physiological and biochemical research, including maturity, shore hardness, soluble solid content, net weight, water loss, α-Mannosidase activity and gene expression of melon fruits after pollination and harvest.Melon fruits transformed by over-expression vector of α-Man gene were ripe about 5 days earlier than the control, which had yellow skin, lower hardness and smaller weight. While melon fruits transformed by RNAi vectors of α-Man gene were ripe about 13 days later than the control, which had green skin, higher hardness and bigger weight.The a-Mannosidase activity increased during the fruit development and the peak accured at DAP40 (Day after Pollination, DAP). The a-Mannosidase activity of melon fruits transformed by over-expression vector was higer than the control and the a-Mannosidase activity of melon fruits transformed by RNAi vectors was lower than the control. During the postharvest storage, a-Mannosidase activity of transgenic melon fruit increased gradually, while the control declined. The a-Mannosidase activity of melon fruits transformed by RNAi vectors was higher than the melon fruit transformed by over-expression. The α-Man gene expression pattern was similar with a-Mannosidase activity.Several genes associated with fruit maturity and softening were selected for the research: PME, XTH2, β-HEX, TBG5, ARF4, EXP5, ACO1, ACO5, ACS1, ACS6, ERF1, ERF4, ETR1, and ER24 genes. Results showed that the expression of these genes were relatively high in melon fruits transformed by over-expression vector of a-Man gene compared with melon fruits transformed by RNAi vectors during fruit development and postharvest storage period.This research showed that the a-Man gene could influence the fruit maturity and softening.