Effect And Mechanism Of MJ On Promoting Dedetached-Leaf Senescence

studies had showed that MJ have many physiological effects. But there was little research on the effect and mechanism of MJ promoting senescence, which is our researches studied. Our experimental materials are detached-leaf discs of apple and pear. The main results were as follows:1. The leaf discs Treated with different concentration (10"7mol~ 10'3mol)of MJ solutions showed that MJ could decrease the chlorophyll content apparently. The effects of MJ on chlorophyll a and chlorophyll b had the same trend as the chlorophyll content.2. All using concentrations ( 10'7mol 籐"'~ 10"3mol -L'1) of MJ could deduce the content of soluble protein. Whether light treatment or darkness treatment could decrease the protein content.3. MJ could regulate protective enzymes梥upereoxide dismutase (SOD), catalase (CAT) and peroxidase (POD). As the concentration of MJ solutions increasing from 4.5xlO~7mol-L"1 to 4.5xlO~3moI-L"', SOD and CAT activities decreased apparently, and the higher concentrations of MJ solutions were, the more they decreased. While MJ had little effect on the activity of POD.4. MJ could increase the level of MDA. The effect of MJ on MDA content enhanced with MJ concentration increasing.5 . MJ could increase ethylene production , which was higher with ImmoM/'ACC. The ACO activity of treated leaves was enhanced within the MJ concentration from 4.5xlO"7mol-L~' to 4.5xlO"3mol-L~1.6. Experiments were conducted by treating leaves with 4.5x10~4mol-L'lMJ and Ca2\ SHAM, STS and EGTA. The results showed that Ca2\ SHAM, STS could inhibit the senescence of treated leaves by MJ, while EGTA could intensify the senescence leaded by MJ.The experimental results indicated that MJ could promote the apple leaves-34-senescence. The possible mechanism had for ways. The first is through inhibiting the activities of protective enzymes, increasing the level of active radical and aggravating lipid peroxidation; MJ could promote senescence by increasing the content of ethylene; The third possible way is to reduce the Ca2+ level of cell; The last mechanism of MJ promoting senescence relates to the ingenerous content of JA.