Study Of Rice Leaf Senescence Physiological Changes And Protein Degradation And Protease Activity

Leaf is the most important photosynthesis organs of crops. Crop yield is significantly affected due to leaf senescence, and thus exploring the mechanisms caused leaf senescence is very important for the improvement of grain yield and quality. During leaf senescence, the assimilatory functions decreased and degraded metabolism accelerated. A large number of proteins accumulated in mature leaves will degraded catalyzed by specific proteases. In this experiment, we investigated the possible mechanisms of rice senescence, using rice variety 93-11 and two leaf senescence mutants as experimental materials. Different treatments were used, including dark treatment, sugar treatment, ABA treatment and 6-BA treatment. The main results are as follows:(1) Chlorophyll content of the three genotypes decreased gradually, TM274 and TM313 chlorophyll content was significantly lower than in the late stage of senescence of wild-type 9311; three MDA content increased, TM313 the largest increase, TM274 but not significant; three POD activity was first increased and then decreased senescence TM313 and TM274 the POD activity was significantly higher than that of wild-type 9311; three CAT activity decreased. TM313 compared with wild-type 93-11 show premature aging trend, TM274 of premature trend is not significant.(2) For in vitro induction of senescence treatments Chlorophyll content of the three genotypes for the more sensitive dark-induced, but not sensitive to sucrose induced, the result is consistent with the phenotypic change; MDA content and POD, CAT activity in the dark is not sensitive to the induction and ABA induction , but sensitive to sucrose induction, and 5% sucrose solution on the more sensitive.(3) For in vitro delay of leaf senesecence treatment Leaf senescence in vitro chlorophyll content, MDA and CAT activity results show that, exogenous 6-BA, applied to a certain extent, delayed leaf senescence, but this delay effect is not significant. In the 6-BA treatment compared with the control the activity of POD was no significant change in the trend did not delay leaf senescence.(4) Soluble protein content of the three genotypes showed a decreasing trend. The three genotypes during leaf senescence showed a total of 6 A ~ E protein bands with molecular weights of> 116kD, 100kD, 55kD, 43 kD, 40 kD, and these bands of activity increased gradually; in section D, 43kD with the TM274 and TM313 in the activity of weak. Dark treatment, 2% and 5% sucrose and ABA treatments three bands of protease activity less and less, while 6-BA and less than the control band, but the band more than the other treatments, which showed that 6-BA to some extent, delayed leaf senescence.