【作者】 周冬生；

【导师】 吴振廷；

【作者基本信息】 安徽农业大学 ， 农业昆虫与害虫防治， 2001， 硕士

【摘要】 通过田间试验、室内生测、生化分析、免疫检测试验，探讨了转Bt基因棉对棉铃虫的抗性规律及其生理学机制。主要结果如下：1转Bt基因棉抗虫性的比较鉴定 以美国Monsanto公司和Delt＆Pine Land公司合作培育的转Bt基因棉“保铃棉32B”为参考，比较鉴定了我国自行培育的第一个转Bt基因棉品种“国抗棉1号”对棉铃虫的抗性，结果表明，两者对棉铃虫的抗性均表现出一致的动态特征，随着生长时期的推进抗虫活性明显下降，不同棉株器官的抗虫活性有差异，嫩叶大于嫩蕾。相应生长时期相应棉株器官“国抗棉1号”抗虫性均低于“保铃棉32B”，抗性等级分别评价为“抗”和“高抗”。2生长前期转Bt基因棉对棉铃虫的抗性 生长前期转Bt基因棉对低龄棉铃虫幼虫具较强的抗虫活性，但不同时期抗性具一定的动态特征，子叶期抗性最强，出真叶后略有下降，随后逐渐上升，至十叶期达顶点，之后又开始下降。暴雨、低温、持续阴雨等异常天气可导致转Bt基因棉抗虫性的明显下降，且需一定的晴天日照后才能逐渐恢复至正常水平。 沿江棉区一代棉铃虫幼虫发生期，正处于转Bt基因棉的生长前期，转Bt基因棉对1龄和2龄幼虫在较短的时间内即表现出较强的杀虫效果，对3龄和4龄幼虫杀虫效果明显下降，但连续取食后最终全部不能存活，对5龄幼虫杀虫效果较差，连续取食后可部分化蛹但化蛹率明显低于对照。 沿江棉区一代棉铃虫幼虫发生期，有必要对周围混种有常规棉花或其它棉铃虫喜食寄主作物的转Bt基因棉田块进行虫量监测，适时进行化学防治。建议防治指标为每百株2龄以上（包括2龄）幼虫20头，用击倒力强而迅速的药剂喷雾防治，必要时发动人力手工逮杀难以防治的高龄幼虫。考虑到转Bt基因棉和Bt制剂中杀虫蛋白可能存在交互抗性，不宜施用Bt制剂。3施肥量、土壤旱涝、环境温度对转Bt基因棉抗虫性的影响 随着施肥量的增加，转Bt基因棉抗虫性明显增强；低肥时转Bt基因棉对棉铃虫低龄幼虫的毒杀作用和对高龄幼虫的抑制生长作用皆明显降低。 土壤水分过多和过少均不利于转Bt基因棉的抗性表达，土壤涝渍可造成转Bt基因棉抗虫性的显著下降，土壤干旱的影响则相对较小。 低温不仅可明显降低转Bt基因棉抗虫基因的表达活性，亦可明显降低己表达了的杀虫蛋白的抗虫活性。高温亦可降低转Bt基因棉抗虫基因的表达活性，但较低温的影响则相对较小；但高温下，己表达于棉株中的杀虫蛋白对低龄棉铃虫幼虫的抗虫活性明显增强。 重视水肥管理对保证转Bt基因棉抗虫性高效表达至关重要。转Bt基因棉田的施肥量应高于常规棉花，重施基肥，生长中后期应及时追肥，以促进转Bt基因棉的前期生长，保证全生长期棉株内杀虫蛋白的高效表达。遇雨时，应及时排涝。干旱时要及时灌水，切忌大水漫灌。各代棉铃虫幼虫发生期，重视各种异常天气（降雨、低温、干旱等）时转Bt基因棉田间的虫量监测，适时进行防治。4转Bt墓因槽抗虫性时间动恋变化及其机理 转Bt基因棉抗虫性呈较明显的时间动态变化，其总体趋势为：子叶期抗虫性为整个生长期的最强，出真叶后略有下降，之后逐渐上升，至十叶期达顶点，整个苗期抗虫性均较强，始蕾期又有所下降，之后整个生长中后期显著下降至最低。 不同生长时期转Bt基因棉中杀虫蛋白含量呈动态变化，且与水溶性蛋白、总蛋白含量正相关极显著。因此棉株中杀虫蛋白含量时间动态变化与棉株中蛋白质代谢直接相关，棉株中蛋白质合成代谢旺盛，棉株杀虫蛋白含量则高。 转Bt基因棉中杀虫蛋白含量与生测抗性正相关极显著，单宁含量与生测抗性则负相关极显著，而单宁可作用于杀虫蛋白造成后者抗虫活性的下降。因此，转Bt基因棉抗虫性时间动态变化最终取决于两个因素，即棉株中杀虫蛋白含量和单宁含量的变化，前者是正相关，后者则是负相关。 转Bt基因棉子叶期抗虫性最强是由于棉籽中杀虫蛋白含量较高。出真叶后略有下降是由于棉株幼苗生长势较弱，蛋白质合成代谢能力相对较弱，随后抗虫性逐渐上升是由于随棉苗的生长，蛋白质合成代谢逐渐旺盛；整个苗期抗性较强是由于苗期仅有营养生长，棉株代谢负担较小，棉株中杀虫蛋白含量较高。始蕾期后抗性开始下降，是由于生殖生长的开始，增加了棉株 2 的代谢负担，整个生长中后期抗性显著下降至最低，是由于后期棉株组织老 化，体内蛋白质的合成代谢减弱而分解代谢增强，杀虫蛋白含量逐渐下降， 同时棉株内单宁含量升高，与杀虫蛋白作用使后者抗虫活性下降。 5转st基困栩对栩铃虫拒加用及娜理 转B工基因棉对3龄以上棉铃虫幼虫的短期致死作用明显降低，但仍具 有一定抗性，其表现形式为拒食作用。取食转st基因棉后，随幼虫龄期的 增加拒食作用明显降低，其中对5龄幼虫的拒食作用很低。取食转Bt基因更多还原

【Abstract】 The resistance of Bt transgenic cotton to cotton bollworm and the physiological mechanisms thereof are probed into by methods of field experiment, chamber bioassay, biochemical and immune determination. The main results are summarized.1. The insect-resistant comparison and evaluation of Bt transgenic cottonThe resistance to cotton bollworm of Bt transgenic cotton "Guo-kang-mian No.l", the first cultivar of tansgenic cotton breed in China, is compared with that of "Bao-ling-mian 32B" introduced from America. Their resistances both show the same time and space dynamic. The resistance descends significantly with the development of cotton growth stages. The resistance also differs with the differences of cotton structures; that is, the resistance of tender leaves is superior to that of tender squares. The resistance of "Guo-kang-mian No.l "is inferior to that of "Bao-ling-mian 32B" at every corresponding growth stage, and the same as every corresponding cotton structure. Their resistant degrees are evaluated at RESISTANCE and HIGH RESISTANCE respectively.2. The resistance to cotton bollworm of Bt trnsgenic cotton during its former growth stagesBt transgenic cotton during its former growth stages shows magnificent insecticidal activity to the lower-instar larvae of cotton bollworm, but the resistance shows dynamic variation with the development of cotton growth stages. The resistance at cotyledon stage is superior to that at any other stage; when the first true leave sprouts the resistance descends slightly, and then increases gradually during the whole seedling stage, until reaches the top at 10-leaf stage; henceforth the resistant descendent starts. The abnormal climates, such as storm, low temperature, consecutive overcast and rainy, can cause the sharp resistant descendent, and it will take several sunny days to restore.During the first generation occurrence stage of the cotton bollworm larvae in Yanjiang Cotton Area, Bt transgenic cotton shows considerable insecticidal efficacy against 1st and 2nd instar larvae, however the efficacy against 3rd and 4thinstar larvae descends significantly; and the efficacy against 5th instar larvae is so poor that part of the larvae can survive to pupa, but the pupation rate is significantly lower than that of CK.The quantity supervision of the first generation larvae should be stressed, especially in the fields interpersed with normal cotton and other host crops preferable to cotton bollworm, so that the chemical control can be operated timely. The suggestive control index is 20 second-instar and above larvae per 100 cotton plants. The powerful and quick chemical pesticides are favorite to be sprayed, when necessarily, the higher-instar larvae with strong adaptability should be killed artificially. Bt Preparations are not recommended in view of the probable mutual resistance of pest.3. The influence of fertilization, soil drought and water-logging, environmental temperature on the insect-resistance of Bt transgenic cottonThe insecticidal activity and the growth inhibition action of Bt transgenic cotton increase with the enhancing of rates of fertilization, and decline sharply at lower-rate. The excess and weakness of water in soil both show detrimental influence on the resistant expression, meanwhile the influence of drought is less than that of water-logging. Lower-temperature can descends considerably not only the expressive activity of Bt gene transformed in transgenic cotton, but also the insecticidal activity of the insecticidal protein having expressed in transgenic cotton. Higher-temperature can also cause the expressive descendent of Bt gene, but its influence is less than that of lower-temperature. However, the insect-resistant activity of the insecticidal protein having expressed in transgenic cotton, under higher-temperature, to the lower-instar larvae of cotton bollworm increases significantly.The management of water and fertilizer in transgenic cotton field is crucial to the efficient insect-resistant expression. The rate of fertiliz更多还原