转基因小黑杨对土壤微生物群落结构的影响

Influence of transgenic Populus simonii × P. nigra on soil microbial community

为评价转基因林木环境释放可能引起的生态风险，以及转基因林木在生产应用中的可行性和可靠性，以实验室种植的转Bt-蜘蛛神经毒肽重组基因的小黑杨为材料，对转基因与非转基因植株根际（通常为几毫米至几厘米）土壤细菌、放线菌、真菌数量和基因水平转移情况进行检测，结果表明：转基因小黑杨种植一段时间后其根系附近的微生物数量略高于非转基因小黑杨。利用卡那霉素选择培养基分离根系周围细菌菌落发现转基因植株周围的土样细菌中，KanR抗性细菌菌落数占总细菌菌落的比例在11．58％～13．00％之间，而非转基因植株根际周围和空白土壤细菌菌落数则在5．73％～6．40％之间，表明转基因小黑杨根系对土壤细菌的抗生素抗性产生一定的影响。利用转基因植株的目的基因和抗性基因设计引物，以土壤中细菌基因组DNA为模板进行PCR扩增，转基因植株种植7个月后，根际土壤细菌菌落中含有抗性基因的菌落数量明显增加。虽然在种植1个月的转基因植株根际土壤土样细菌中未检出目的基因，但在种植7个月后的土样中检验到了很少的目的基因阳性细菌，阳性细菌菌落比例为2％～5％，检测结果表明可能有极少数Bt-蜘蛛神经毒肽重组基因发生了水平转移。

In order to evaluate the possibility of the ecological risk caused by releasing transgenic trees and the feasibility of applying transgenic trees in forest production,the transgenic Populus simonii＆#215;P.nigra with Bt-the spider insecticidal peptide recombinant gene was used as the material.Three kinds of rhizosphere soil microbe including bacteria, actinomy-ces and fungi were isolated and counted by plate dilution, and the target and resistance gene of transgenic trees were am-plified by PCR inbacteria. The result showed that the microbial number in transgenic plants rhizosphere soil was a little more than that in non-transgenic soil after the seedlings planted for seven months. From the antibiotic resistance test, the percentage of the antibiotic-resistant bacteria was 11. 58% and 13. 00% from two transgenic plants rhizosphere soils re-spectively, but the non-transgenic plants rhizosphere soil and soil control was only 5.73% and 6.40%, which indicated that the root litter of transgenic poplar could impact on antibiotic resistance of the soil bacteria. The primers were de-signed according to the target gene and resistance gene sequence of the transgenic poplar, and the PCR reaction was done using genomic DNA of the bacterial clones as the template. The number of bacteria in transgenic plants rhizosphere soils containing the resistance gene increased significantly after planting 7 months. The positive bacteria of the target gene from the soil bacterial clones could be detected in 7 months planting with percentage 2% and 5%, which indicated a pos-sibility that the Bt-the spider insecticidal peptide gene maybe occur horizontal transfer.