Bt棉生殖器官发育与Bt杀虫蛋白表达量关系及氮代谢生理机制

The reproductive organs are first targets when the boll worm harm cotton.It is important to study effect of the reproductive organs development on its insecticidal protein expression and related physiological mechanism for safty application of the insect resistance and high efficient expression for both the insect resisitance and yield potential of the yield organs in Bt cotton. the studies will be conducted on the effect of Bt insecticidal protein concentration of the square and boll and the characteristics of nitrogen metabolism that related to protein synthesis and degradation under different quantity of square and boll for whole plant,the strengthen and weaken for square and boll development.The affected extent of insect resistance of the square and boll and nitrogen metabolic physiological mechanism will be probed under different number of square and boll, dry matter weight of square and boll for whole plant,ratio for square and boll weight in whole cotton plant, different volume, weight and growth rate of the square and boll respectively.These investigation will provide biological and physiological basis for diagnosing the change characteristics of insect resistance under different development of the yield organs(square and boll), and achieving the high efficient expression for both the insect resistance and yield potential of the yield organs in Bt cotton.

棉花的生殖器官作为棉铃虫危害的首选目标，研究Bt转基因棉生殖器官发育状况的变化对其Bt杀虫蛋白表达量影响及相关生理机制对于确保Bt棉花抗虫性在生产上安全应用，促进产量器官抗虫性和丰产性协同表达具有重要意义。本项目拟通过研究整株蕾量和铃量的变化、蕾铃发育加快和减慢条件下Bt棉蕾和铃Bt杀虫蛋白表达量的变化及其蛋白质合成及分解的氮代谢生理特征。明确棉株蕾铃数量、生物量，生物量占整株比例，蕾铃的体积、重量及其增长速率的变化对蕾和铃抗虫性的影响程度及及其氮代谢生理机制。为更准确把握我国Bt转基因棉花在产量器官（蕾和铃）发育不同状态下抗虫性变化特征、并为实现产量器官抗虫性和丰产性协同表达提供生物学和生理学基础。

为明确Bt棉发育旺盛期蕾铃抗虫性表达低的原因，本课题以Bt棉常规种泗抗1号（S1）、杂交种泗抗3号(S3)为材料，设计密度、肥料、剪叶、去蕾等试验，探讨棉株蕾铃数量、质量及其增长速率的变化对其杀虫蛋白表达量影响及其氮代谢生理机制。结果如下：.1 密度、施氮量变化引起棉株蕾数和蕾干重、单蕾体积和干重增加同时，蕾的Bt蛋白含量也相应增加。在常规氮肥用量50%变化范围内，蕾量在8.9-29.1个/株，蕾Bt蛋白浓度可调程度为1.8%-19.5%。在常规密度水平100%变化范围内，蕾量在10.3-22.5个/株，蕾Bt蛋白浓度可调程度2.8-30.8%。单株蕾干重、单蕾体积和干重变化对蕾Bt蛋白影响呈相似的结果。棉株蕾数和蕾干重、单蕾体积和干重日增量增加同时，蕾的Bt蛋白浓度日增量同样也相应增加。.　　单株蕾数和干重、单蕾体积和单蕾重及其增长量与蕾中Bt蛋白含量及增长量基本都呈显著以上水平正相关。.2 密度、施氮量变化引起单株铃数、单铃体积和干重增加同时，铃壳、棉子（施氮试验棉子正相反）和纤维的Bt蛋白浓度下降。在常规氮肥用量50%变化范围内，铃量在4.7-20.3个/株范围内，铃壳Bt蛋白含量可调范围为7.3-42.3%，棉子为7.5-32.3%，纤维为13.5-56.8%。在常规密度水平100%变化范围内，铃量在1.7-9.3个/株范围内，铃壳Bt蛋白含量可调范围为2.8-21.5%，棉子为7.6-40.0%，纤维为8.7-48.9%。单铃体积和干重变化对铃Bt蛋白影响呈相似结果。成铃强度、铃体积和干重日增量增加的同时,铃壳、棉子和纤维中Bt蛋白日增量下降（施氮试验棉子的结果相反）。.单株铃数、单铃体积和单铃重及增长量变化与铃壳、纤维中和棉子Bt蛋白含量基本上呈显著以上水平负相关（施氮试验棉子呈相反结果）。.上述结果在剪叶、去蕾和喷施DPC试验中得到进一步验证。. 3 蕾铃中可溶性蛋白含量、GPT和GOT活性上升，游离氨基酸含量、蛋白酶和肽酶活性下降有利于蕾铃Bt蛋白含量提高。反之则会引起下降。.因此，培育蕾大蕾多、铃数和大小适中的品种，促进棉蕾发育、控制棉铃适度形成和发育，有利于提高蕾铃Bt杀虫蛋白含量，增强抗虫性。