Jiang Zhilei, Zhou Lei, Wang Baifeng, Yin Junqi, Wu Fengci, Wang Daming, Li Liang, Song Xinyuan
Jilin Provincial Key Laboratory of Agricultural Biotechnology, Agro-Biotechnology Research Institute, Jilin Academy of Agricultural Sciences, Changchun, China.
Institute of Quality Standard and Testing Technology for Agro-products, Chinese Academy of Agricultural Sciences, Beijing, China.
Front Plant Sci. 2022 Apr 13;13:875020. doi: 10.3389/fpls.2022.875020. eCollection 2022.
(Bt) protein expressed by genetically modified (GM) crops is released into the soil ecosystem, where it accumulates for a long time; therefore, degradation of Bt protein has gained increased attention for environmental risk assessments. A first-order kinetic model ( = ae) is usually used to evaluate the degradation of Bt proteins, including Bt-Cry1Ab and Bt-Cry1Ac; this has some limitations regarding the precise fitting and explanation of the influence of various factors on Bt protein degradation in the later stage. Therefore, to amend these limitations, we report a new degradation model = Y + ae. The effects of soil temperature, water content, soil types, and soil sterilization on the degradation of Bt-Cry1Ah protein in soil were estimated in a 96d long laboratory study using a GM maize leaf-soil mixture. The results showed that the Bt-Cry1Ah protein degraded rapidly in the early stage and then slowly in the middle and late stages. Temperature was identified as the key factor affecting the degradation of Cry1Ah protein-a relatively higher temperature favored the degradation. The degradation rate of Cry1Ah protein was the fastest when the water content was 33 and 20% in the early and later stages, respectively. The soil types had a significant effect on the degradation of Cry1Ah protein. Moreover, soil sterilization slowed down the rate of protein degradation in both the early and later stages. In conclusion, the model = Y + ae established in this study provided a more robust model for exploring and simulating the degradation of Bt protein in soil growing GM crops and overcame the shortcomings of the = ae model. The findings of this study enriched the understanding of Bt protein degradation in soil ecosystems. They would be helpful for evaluating the environmental safety of GM crops.
转基因（GM）作物表达的（Bt）蛋白释放到土壤生态系统中，并在那里长期积累；因此，Bt蛋白的降解在环境风险评估中受到了越来越多的关注。通常使用一级动力学模型（=ae）来评估Bt蛋白（包括Bt-Cry1Ab和Bt-Cry1Ac）的降解；但该模型在精确拟合以及解释后期各种因素对Bt蛋白降解的影响方面存在一些局限性。因此，为了修正这些局限性，我们报告了一种新的降解模型=Y+ae。在一项为期96天的实验室研究中，使用转基因玉米叶-土壤混合物，评估了土壤温度、含水量、土壤类型和土壤灭菌对土壤中Bt-Cry1Ah蛋白降解的影响。结果表明，Bt-Cry1Ah蛋白在早期快速降解，然后在中期和后期缓慢降解。温度被确定为影响Cry1Ah蛋白降解的关键因素——相对较高的温度有利于降解。Cry1Ah蛋白的降解率在早期含水量为33%、后期含水量为20%时最快。土壤类型对Cry1Ah蛋白的降解有显著影响。此外，土壤灭菌在早期和后期都减缓了蛋白质的降解速度。总之，本研究建立的模型=Y+ae为探索和模拟转基因作物种植土壤中Bt蛋白的降解提供了一个更强大的模型，并克服了=ae模型的缺点。本研究结果丰富了对土壤生态系统中Bt蛋白降解的认识。它们将有助于评估转基因作物的环境安全性。
