Abstract:Transgene stability, the changes in species and quantity of microorganisms in soil after planting, and horizontal gene transfer are important parts for evaluating biosafety risks in transgenic plants. The transgenic hybrid of Populus〔(Populus tomentosa ×P. bolleana)×P. tomentosa〕carried AhDREB1 gene has been planted for 3 years in Dongying city Shandong province. Transgene stability of the transgenic hybrid Populus was analyzed by PCR technology, AhDREB1 gene was still existed in the transgenic trees. The flat dilution and analysis of variance was used to survey three groups of microorganisms (bacterium, actinomyces and epiphyte) in the soil around the roots, no significant difference was found in terms of the number of microorganisms between non- and transgenic trees. And no alien target DNA was detected from PCR products of total soil DNA and strains DNA amplified with specific primers of AhDREB1. It indicated that transgene was stable in the transgenic hybrid of Populus after 3 years planting, and no significant negative effect on soil microorganisms system had been found yet.