抗草丁膦和抗草甘膦转基因油菜的抗性基因向野芥菜的流动

通过人工去雄授粉和田间隔行种植试验,研究了抗草丁膦和抗草甘膦转基因油菜(Brassica napus)中的bar基因和EPSPS基因向野芥菜(B. juncea var. gracilis)流动的可能性。结果表明在人工授粉的情况下,以野芥菜为母本,分别以两种转基因油菜为父本,亲和性指数都很高,达13以上,与野芥菜自交或开放授粉条件下的亲和性指数没有明显差异,说明两种转基因油菜和野芥菜的亲和性较好。经两次除草剂筛选,人工杂交获得的所有F₁对相应的除草剂都表现出了明显的抗性,且经PCR检测扩增出了各自的特异性条带,说明人工杂交获得的所有F₁都携带了相应的抗性基因。F₁的适合度研究表明,两种F₁种子萌发率和母本都没有明显差异,营养生长明显好于母本。但花粉活力和结实率明显下降,携带抗草丁膦基因F₁的花粉活力和每角果粒数分别是32.4%和0.59粒,携带抗草甘膦基因F₁的花粉活力和每角果粒数分别是35.1%和0.58粒。经两次除草剂筛选和PCR检测,表明野芥菜和抗草丁膦油菜或与抗草甘膦油菜田间隔行种植分别能产生0.02%和0.014%的携带抗性基因的F₁杂种。以上结果表明抗除草剂转基因油菜的抗性基因具有向野芥菜流动的可能性,且bar和EPSPS基因向野芥菜流动的可能性类似,但对其可能引起的环境后果需要做进一步地深入研究。

GENE FLOW FROM TRANSGENIC GLUFOSINATE- OR GLYPHOSATE-TOLERANT OILSEED RAPE TO WILD RAPE

Aims Wild rape (Brassica juncea var. gracilis), a wild relative of oilseed rape (B. napus), was chosen for a case study because gene flow from herbicide-resistant oilseed rape to wild rape rarely has been explored. We asked a) are transgenic herbicide-resistant oilseed rape and wild rape sexually compatible, b) is the fitness of their F₁ improved and c) is gene flow possible?Methods We used hand pollination to test sexual compatibility and examined resistance of the F₁ by applying herbicide of 2 000 μg a.i.·kg^-1 with 0.1 L·m^-2 volume at 3-4 leaf stage twice and by PCR and examining vegetative growth, pollen viability and seed setting rate. Crossing from herbicide-resistant oilseed rape to wild rape also was tested under open pollination.Important findings Indexes of sexual compatibility of wild rape×glufosinate-tolerant oilseed and wild rape×glyphosate-tolerant oilseed were 13.87 and 13.83, respectively, under hand pollination, and these indexes were not significantly different from that of the female parent under self pollination and open pollination. All F₁ were significantly resistant to the corresponding herbicide. Moreover, herbicide-resistant gene of F₁ was confirmed by PCR and F₁ of wild rape×glufosinate-resistant oilseed and wild rape×glyphosate-resistant oilseed produced 426 bp and 931 bp identical special band, respectively. The fitness of the F₁ changed compared with that of the female parent. The germination rate of the F₁ was similar with that of the female parent, >98%. Due to taller individuals and larger leaves, the vegetative growth of the F₁ was much better than that of the female parent. However, pollen viabilities of both kinds of F₁ were only half that of the female parent. Furthermore, the seed number per silique of the F₁ was very low, only 0.59 and 0.58 seeds per silique, respectively. The cross rate of wild rape×glufosinate-resistant and wild rape×glyphosate-resistant was 0.02% and 0.01%, respectively, under open pollination. Our study suggests the possibility of gene flow from transgenic rape to wild rape. The possibilities of gene flow from the two herbicide-resistant transgenic oilseed rapes to wild rape were similar under hand pollination or open pollination. However, the effect of gene flow from transgenic herbicide-resistant oilseed to wild rape needs further research.