论文标题:转Bt基因棉花和水稻Cry1Ac杀虫蛋白在不同环境中的消长动态
Environmental Dynamics of Insecticidal Proteins from Transgenic Cry1Ac Cotton and Rice
论文作者 李云河
论文导师 原国辉；吴孔明,论文学位 硕士,论文专业 农业昆虫与害虫防治
论文单位 河南农业大学,点击次数 697,论文页数 51页File Size2037k
2005-06-01论文网 http://www.lw23.com/lunwen_166827/ Bt杀虫蛋白;生态风险;土壤系统;降解动态;残留
Bt insecticidal protein; ecological risk; soil system; degradation dynamic;persistence
本文以转Bt棉新棉33B和转Cry1Ac/CpTI双价基因水稻MSA和MSB为材料,采用ELISA-Cry1Ac蛋白定量测定法研究了转Bt基因作物组织中的杀虫蛋白在不同环境中的残留及降解动态。取得了如下结果: 1.转Bt-cry1Ac基因棉花组织中杀虫蛋白在环境中的降解动态 大田和试验室研究了Bt棉花叶片中Cry1Ac杀虫蛋白在土壤介质中和不同环境条件空气介质中的降解动态规律。结果表明,不同环境下Bt杀虫蛋白降解趋势有明显差异。在不同温湿度及光照条件的空气介质中,Bt蛋白的降解速度一般在初期较快,经过短暂的缓慢降解阶段后进入相对稳定状态(50ngg~(-1)左右)。温度较高,湿度较小,Bt杀虫蛋白降解较快,达到稳定水平的时间短。光照和非光照条件下的Bt棉叶中杀虫蛋白的降解动态一致,没有显著性差异。自然条件下Cry1Ae蛋白在土壤介质中初始阶段降解迅速,30天后降解85%左右。随着冬季的到来,杀虫蛋白降解趋于缓慢。次年春天后,杀虫蛋白降解速度加快,到4月下旬已全部降解。 2.Bt棉田土壤中Bt杀虫蛋白的残留监测 ELISA技术检测了转Bt棉花生长期根际土壤及多年种植Bt棉田土壤,结果没有发现Bt杀虫蛋白在土壤中的残留。在一定程度上说明了Bt棉花的大量、多年重复种植不会导致Bt毒蛋白在土壤中逐年累积。 3.转CryAc/CpTI双价抗虫水稻组织中Cry1Ac杀虫蛋白的表达动态 检测了Bt稻主茎和根中在不同生长期Cry1Ac蛋白的表达水平及根系的分泌情况。结果表明:转双价基因水稻MSA和MSB的根茎中在整个生育期都能表达Bt杀虫蛋白,主茎中的表达量在各生长阶段都明显高于根中。不同生长阶段MSA和MSB根茎中Bt杀虫蛋白的表达动态基本一致,都表现为初期低,中期高,晚期有所下降;分蘖期、拔节期及孕穗期Bt水稻根部分泌物中都能检测到Bt杀虫蛋白,但分泌量很低,以至用ELSA检测法很难精确定量。 4.大田环境下Bt稻根茬中Bt杀虫蛋白的降解动态 水稻收获后用ELISA技术检测了根茬中Cry1Ac杀虫蛋白大田环境中残留动态。结果显示:Bt杀虫蛋白能在根茬中长期残留,试验进行7个月后,仍然能检测到Bt杀虫蛋白的存在。根茬中Bt杀虫蛋白的降解表现初期降解非常迅速;进入冬季,降解速度明显减慢,甚至不降解;次年春天,Bt杀虫蛋白的含量又开始下降。然而,随着根茬地上部分的逐渐干燥,Bt杀虫蛋白的降解越来越慢,甚至进入保持较低含量长期稳定的状态;在潮湿土壤中的地下部分,Bt杀虫蛋白能持续降解,有短期内全部降解的趋势。 5.Bt水稻组织释放的Cry1Ac蛋白在土壤及水中的降解 试验初期,打碎的水稻组织释放的Cry1Ac蛋白在土壤中的降解速度明显大于在水中的降解速度。但30天后,土壤中残留的Cry1Ac蛋白几乎不再降解,保持在较低的含量水平长期不变;
Transgenic Bt cotton NUCONT33~B and transgenic Cry1Ac/CpTI rice lines, MSA and MSB, containing a synthetic cry1Ac gene from Bacillus thuringiensis, were used to study the resistance and degradation dynamics of Bt insecticidal proteins in the tissues of Bt crops under different situations by ELISA. The results are as fellows:1. Degradation dynamics of Cry1 Ac insecticidal protein in Bt cotton tissues under differentenvironmentsThe degradation dynamics of Cry1 Ac insecticidal protein in Bt cotton with exposure to air and soil mediums under different conditions were investigated in the laboratory and field. The results showed that the degradation trends under different situations were significantly different. In general, Bt protein in cotton leaves degraded rapidly in first several days, then got slowly and entered a relative stable stage in which Bt protein content kept at a concentration of 50ngg~(-1). The higher temperature and lower humidity significantly increased degradation speed of the toxin, which resulted in a short period for the content of the protein to get into stable stage. However, there were no significant differences in degradation between light and dark treatments. In natural environment, the insecticidal protein in Bt cotton degraded much rapidly in the initial period, it reached 85% in first month, and stopped during winter season, then degraded quickly in next spring until disappeared in late April.2. Detection of persistence of Bt insecticidal protein in Bt cotton fieldDetected rhizosphere-soil of the growing Bt cottons and the soil in the fields where Bt cottons have been planting for multiple years, but non-Bt-insecticidal -proteins were found. The result showed on a certain extent that to plant Bt cottons widely and repeatedly could not result in accumulations of Bt insecticidal protein in soil.3. Expressing dynamics of Cry1 Ac protein in the tissues of Bt rice.The expressing levels of Bt insecticidal proteins in the root and main stalks of Bt rice lines, MSA and MSB, at different stages were investigated by ELISA. The results showed
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