抗草甘膦转基因油菜和野芥菜回交1代子2代-子6代在无除草剂选择压下的适合度

Fitness of the first backcross generations from the second to the sixth progenies of glyphosate-resistant transgenic Brassica napus and wild Brassica juncea in absence of the herbicide

抗草甘膦转基因油菜和野芥菜回交1代子2代-子6代在无除草剂选择压下的适合度转基因作物的抗性基因能否成功渗入野生或近缘杂草取决于携带转基因回交后代的适合度。为深入了解转基因油菜(Brassica napus)向野芥菜(wild B.juncea)基因流动的生态风险,本文研究了在低密度(5株/m^(2))和高密度(10株/m^(2))下,以及单种和混合种植(野芥菜:BC1F2R-BC1F6R=1:1)下抗草甘膦转基因油菜与野芥菜回交1代子2代到子6代(BC1F2R-BC1F6R)的适合度;并分析回交后代的适合度成分、种植密度和种植方式之间的相关性。研究结果表明:在单种低密度下,与野芥菜相比,回交1代子2代(BC1F2R)和子3代(BC1F3R)具有较低的适合度,而回交1代子4代-子6代(BC1F4R-BC1F6R)具有较高的适合度;无论是单种还是混种,高密度下所有回交后代的适合度均低于野芥菜。相关性分析结果显示,种植密度和种植方式对回交后代(BC1F2R-BC1F6R)的适合度成分有显著影响。这些结果表明,转基因从栽培油菜渗入到野芥菜很大程度上取决于回交后代的特定生长环境。

Successful introgression of a transgene from a transgenic crop into a wild or weedy relative is determined by the fitness of backcross generations carrying the transgene.To provide insight for ecological risk assessment of gene flow between transgenic Brassica napus and wild Brassica juncea,this study investigated the fitness of the first backcross generations from the second to the sixth progenies(BC1F2R-BC1F6R)between glyphosate-resistant transgenic B.napus and wild B.juncea at low density(5 plants/m^(2))and high density(10 plants/m^(2)),and monoculture and mixed planting(wild B.juncea:BC1F2R-BC1F6R=1:1).Correlations between the fitness components of backcross progeny,planting density and planting patterns were analyzed.In the monoculture at low density,compared with B.juncea,earlier generations BC1F2R and BC1F3R had low composite fitness,while later generations from BC1F4R to BC1F6R were more fit.At high density,whatever monoculture or mixed planting,all backcrossed generations had lower composite fitness than B.juncea.Correlation analysis indicated that both planting density and pattern significantly affected the fitness components of the first backcross generations from the second to the sixth progenies(BC1F2R-BC1F6R).These results indicate that the probability of transgene introgression from cultivated B.napus to weedy B.juncea is likely to be highly contingent on the specific growing conditions of their backcross descendants.