Effects Of Nitrogen Management Practices On Expression And Degradation Of Bt-protein In Transgenic Cotton

In this paper,transfer gene unit hybrid cotton zhongmian72 was used as experimental material, using different nitrogen fertilizer rates and patterns treatments, the effects of nitrogen management practices on expression and degradation of Bt-protein in leaves and bolls and its preliminary mechanism,the effects of nitrogen management practices on the content of Bt-protein in squares,the effects of nitrogen management practices on the activities of nitrogen metabolism and senescence in the leaves were studied. The results as follows:1 The effects of nitrogen management practices on expression and degradation of Bt-protein in leavesWith the growth of the leaves,the content of Bt-protein showed that first increased and then decreased,it was maximum in leaves of functioning stage, it declined obviously in leaves of senescing stage and shedding stage.The nitrogen can regulate expression and degradation of Bt-protein in leaves. In terms of nitrogen fertilizer rates treatments, with the increasing amount of nitrogen fertilizer,the content of Bt-protein trend to increase,but when the nitrogen fertilizer was excessive, the content of Bt-protein will decrease. The later residues were more when Bt-protein expressed more in prophase. In terms of nitrogen fertilizer patterns treatments, if the base fertilizer is not applied, the expression of Bt-protein will be affected;when using more fertilizer of roofing,the rate of degradation of Bt-protein will be slow,the residual Bt-protein were numerous.2 The effects of nitrogen management practices on expression and degradation of Bt-protein in bollsWith the development of boll,the content of Bt-protein in shell showed that first increased and then decreased,it was maximum in the stage of filling,it rapid declined in the stage opening. The content of Bt-protein in the seed will increase,it was maximum in the stage of opening. With the increasing amount of nitrogen fertilizer, the contents of Bt-protein in shell, fiber and seed of bolls were increasing in the mass, the later residues were more when Bt-protein expressed more in prophase. The expression and degradation of Bt-protein in the boll was affected by different nitrogen fertilizer patterns. The contents of Bt-protein in shell, fiber and seed of bolls of treatment B3 were more than other treatments in the stage of expanding and filling; in the stage of opening, the contents of Bt-protein in the organs of boll of treatment B1 were more than other treatments because of using major fertilizer of roofing, the contents of Bt-protein of treatment B4 were minimal.3 The effects of nitrogen management practices on the activities of nitrogen metabolism in leavesThe activities of nitrogen metabolism in leaves were obviously affected by nitrogen fertilizer rates treatments, the content of amino acids,soluble protein,total nitrogen and Glutamine synthase (GS) activity in leaves increased with the nitrogen fertilizer rates. The activities of nitrogen metabolism in leaves were also obviously affected by nitrogen fertilizer patterns treatments, the content of amino acids,soluble protein,total nitrogen and Glutamine synthase (GS) activity in leaves in treatments B4 were higher than others in the stage of expanding, the activities of nitrogen metabolism in leaves in treatment B1 were stronger than others in the stage of senescing and shedding. This shows that using a certain amount of fertilizer of roofing can evidently improve the activities of nitrogen metabolism in late stages.4 The effects of nitrogen management practices on the characteristic of senescence in leavesThe content of the malondialdehyde(MDA) and chlorophyll,the activity of superoxide dismutase (SOD) in leaves under different nitrogenous fertilizer treatments were assayed, the results showed that the content of the malondialdehyde(MDA) reduced,the activity of superoxide dismutase (SOD) enhanced,the content of chlorophyll increased in leaves with the increasing of nitrogenous fertilizer,the process of the senescence of leaves was delayed.In terms of nitrogen fertilizer patterns treatments, the content of the malondialdehyde(MDA)was lower,the activity of superoxide dismutase (SOD) and the content of chlorophyll were hinger than other treatments in the stages of expanding and functioning inleaves withmore base and boll fertilizer. the content of the malondialdehyde(MDA) was lower,the activity of superoxide dismutase (SOD) and the content of chlorophyll were hinger than other treatments in the stages of senescing and shedding in leaves with more roofing fertilizer.These show that applying fertilizer in time for transgenic cotton can prevent the premature senescence because of lack of fertilizer,and then the process of the senescence of leaves was delayed.5 The preliminary mechanism of the effects of nitrogen management practices on expression and degradation of Bt-protein in leavesIn terms of nitrogen fertilizer rates treatments, the content of amino acids,soluble protein,total nitrogen and Glutamine synthase (GS) activity in leaves increased with the nitrogen fertilizer rates in expanding stage﹑functioning stage,senescing stage and shedding stage.At the same time, the synthesis of Bt-protein was promoted, led to the expression of Bt-protein increased in the early growth stage,the residues in the late growth stage were large. For nitrogen fertilizer patterns treatments, the treatment B4 because of base fertilizer and boll fertilizer applied more, the content of amino acids,soluble protein,total nitrogen and Glutamine synthase (GS) activity were promoted in the stage of expanding, the expression of Bt-protein also increased. The activities of nitrogen metabolism in leaves of treatment B1 were stronger than others in senescing stage and shedding stage, the residues were more than others.