影响Bt稻离体叶中Cry1Ab杀虫蛋白降解的环境因子研究

Impacts of Environmental Factors on Degradation of Cry1Ab Insecticidal Protein in Leaves of Bt Rice

目的研究转Bt基因水稻表达的外源Bt杀虫蛋白在土壤中的环境去向,以便进行转BT基因水稻的生态风险性评价。方法室内采用ELISA法,研究转Bt基因水稻克螟稻2号(KMD2)粉碎叶片中Cry1Ab杀虫蛋白在3种水稻土,即青紫泥田、黄筋泥田和黄松田土中不同土壤含水量、土壤pH值和温度条件下的降解动态。结果供试叶片粉中Cry1Ab蛋白在3种水稻土中的降解动态均可用一级化学反应动力学指数方程来拟合,降解半消减期t0.5为1.8～4.0d。结论土壤含水量、pH和温度对Cry1Ab蛋白降解速率均有一定影响,但pH和温度的影响更为明显。通常pH较低的酸性土壤和低温不利于土壤中Cry1Ab蛋白的降解,特别是在酸性黄松田中降解最慢。

[Objective] The environmental fate of Bt insecticidal protein released by Bt rice plants in paddy soils is a key issue in its ecological risk assessment. [Method] In the present study, impacts of soil water content, pH and temperature on the degradation of CrylAb protein expressed in leaves of Bt rice KMD2 were studied in the laboratory. Three types of paddy soils were used, i.e., blue clayey paddy soil, pale paddy soil on quaternary red soil, and marine-fluvigenic yellow loamy paddy soil. Ground powders of KMD2 leaf-blades were mixed with each type of soil, and degradation dynamics of CrylAb were determined using standard ELISA QuantiplateTM kit （EnviroLogix, USA）. [ Result ] The degradation rate of Cry 1Ab was high at the early experimental stage, but it slowed down steadily at middle and later stages, which could be described by exponential equations with the half-life period of degradation determined as 1.8-4.0 d. [Conclusion]The soil water content, pH and temperature could affect the degradation of Cry 1Ab, but soil pH and temperature were relatively greater. In general, Cry 1Ab degradations were slower under lower soil pH and temperature conditions, especially for marine-fluvigenic yellow loamy paddy soil.