多年种植Bt稻后外源蛋白在土壤中的积累

外源蛋白在环境中的残留与积累是转Bt基因作物环境安全评价的重要内容之一。我国已育成多个具有商业化前景的Bt稻品系,但目前多年种植Bt稻后Bt外源蛋白是否会在土壤中积累还不清楚。本研究在同一试验田连续9年种植了转cry1Ab/1Ac基因明恢63(华恢1号)和转cry2A基因明恢63水稻,采用酶联免疫吸附法(ELISA)跟踪监测了分蘖期和收获后60 d根际土中外源蛋白含量变化,试验第1年(2012年)和最后1年(2020年)还测定了苗期、开花期和成熟期根际土中外源蛋白含量。结果表明: 2012年,转cry1Ab/1Ac基因明恢63在苗期、分蘖期、开花期、成熟期和收获后60 d根际土中外源蛋白含量分别为1.25、1.77、1.97、1.71和0.30 ng·g^-1,2020年分别为1.30、1.69、2.03、1.77和0.43 ng·g^-1;2012年,转cry2A基因明恢63在苗期、分蘖期、开花期、成熟期和收获后60 d根际土中外源蛋白含量分别为0.91、1.52、1.53、1.37和0.12 ng·g^-1,2020年分别为0.95、1.43、1.61、1.40和0.15 ng·g^-1。多因素方差分析显示,时间效应对Bt外源蛋白积累不显著,而品种和生育期效应显著。Bt稻生长过程中根际土中可以检测出微量的Bt外源蛋白,但收获后60 d已经基本降解完毕,根际土中Bt外源蛋白含量不会随着种植时间的增加而累积。

Accumulation of Cry proteins in soil released from Bt rice after planting for multiple years

Cry protein residue and accumulation in soil are two important components of the environmental safety assessment for the plantation of transgenic Bt crops.Several Bt rice lines with good commercial prospects have been developed in China,but it is unclear whether Cry proteins will accumulate in soils after multiple years of Bt rice cultivation.We planted the transgenic Bt rice lines cry1Ab/1Ac Minghui 63(Huahui No.1) and cry2A Minghui 63 for 9 years in the same field.The Cry proteins in the rhizosphere soil were estimated with enzyme linked immunosorbent assay(ELISA) at tillering stage and on the 60 th day after harvest in each year.The Cry protein residues during the seedling,flowering and ripening stages were estimated in the first year(2012) and the last year(2020) of the experiment.In 2012,the concentration of Cry1Ab/1Ac in the rhizosphere soil of Huahui No.1 was 1.25,1.77,1.97,1.71 and 0.30 ng·g^-1 at the seedling,tillering,flowering,ripening stages and on the 60 th day after harvest,respectively.In 2020,the corresponding values were 1.30,1.69,2.03,1.77,and 0.43 ng·g^-1.In 2012,the concentration of Cry2A in rhizosphere soil of line cry2A Minghui 63 was 0.91,1.52,1.53,1.37,and 0.12 ng·g^-1 at the seedling,tillering,flowering,ripening stages and on the 60 th day after harvest,respectively.The corresponding values in 2020 were 0.95,1.43,1.61,1.40,and 0.15 ng·g^-1.Results of multi-way ANOVA showed that the effect of year was not significant,but the effects of rice variety and growth stage were significant.Our results indicated that Cry proteins could be detected in rhizosphere soil during the growth stages of Bt rice,but would be degraded by 60 d after harvest,and that the concentrations of Cry proteins in the soil would not accumulate across multiple planting years.