关键词: 转基因杨树, 田间试验, 安全性

Abstract:

Objective: Potential risks may exist in field plantings of the transgenic trees, four aspects were comprehensively investigated, including the genetic stability of different exogenous genes in the transgenic poplars and the risk of transfer of the exogenous genes to soil microorganisms, the impact of transgenic poplar on soil microbial community and allelopathy to wild plants, the safety of the three types of transgenic poplars for field release were evaluated as a case study for the safety assessment and field release of transgenic trees. Method: The three exogenous genes encoding different resistance proteins (PeTLP, Cry1Ac, ATGols) were constructed into plant expression vector pGWB9. Agrobacterium tumefaciens LBA4404 was used to infect the leaf discs of poplar trees of Nanlin895 (Populus deltoides×P. euramericana 'Nanlin895'), and the positive plants were screened. A total of 13 lines of three types of transgenic poplar Nanlin895 (TLP, Bt, Gols) were obtained and cultured in greenhouse for 1 year. The stem segments were cut and planted in the experimental field. Randomized block design and split-plot design were used in the field planting. The environmental conditions and growth status of the transgenic trees were recorded during the 20 month test period. Leaf samples and soil samples surrounding the sample trees of each transgenic lines and control trees were collected regularly. The genetic stability of three exogenous genes in transgenic poplar was detected by PCR technology, and the total DNA of soil microorganism was extracted for PCR detection of the three exogenous genes, to evaluate the risk of exogenous genes transfer to soil microorganisms. Plate counting method was used to analyze the composition and change of soil microbial community, and the influence of transgenic poplars on soil microbial community was evaluated; the allelopathy of transgenic poplars on wild plants was simulated by 'sandwich' method with lettuce seeds, and the development data of radicle and hypocotyl of lettuce seeds were recorded and analyzed in order to evaluate the impact of transgenic poplars on ecological diversity. Result: The environment conditions of the test field were relatively stable, and there was no extreme weather affecting poplar growth. The growth trend of transgenic poplars was basically consistent with that of the control (poplar Nanlin895), and no significant difference of tree height was found between the transgenic trees and their respective control. The exogenous genes in the transgenic trees were stable, and gene transfer from transgenic trees to soil microorganisms was not found. The quantity of soil microorganisms was significantly affected by temperature and precipitation (P < 0.05), and the community structure and growth of soil microorganisms were not significantly affected by the transgenic trees. The leaves of the transgenic trees with three different exogenous genes had no significant effect on root and hypocotyl growth of the lettuce seeds. Conclusion: Bt, TLP and Gols transgenic trees of poplar Nanlin895 had no obvious environmental hazards in the field testing.

Key words: transgenic poplar, field trial, safety