小麦转基因系中B、D基因组上的Bar基因转移至联合山羊草中的风险评价

Risk Assessment of Bar Gene Transfer from B and D Genomes of Transformed Wheat (Triticum aestivum) Lines to Jointed Goatgrass (Aegilops cylindrica)

通过调查杂交和回交后代的结实率 ,评价小麦转基因系中位于 B、 D基因组上的 Bar基因向联合山羊草转移的风险。B基因组含有 Bar基因的 Bobwhite 3 1系、D基因组含有 Bar基因的 Bobwhite 71系和联合山羊草作为亲本。采用不去雄、天然授粉 ,去雄、天然授粉和去雄、人工授粉 3种授粉方式以鉴定不同授粉方式对 Bar基因转移的影响 ;通过测定回交后代 Bar基因抗性植株的比例对分别位于 B基因组和 D基因组中的Bar基因进行安全评价。结果表明 ,在不去雄、天然授粉的条件下 ,结实率是非常低的 ,在本次试验中未得到种子。但是 ,在人工授粉条件下 ,可以获得杂种。基因位点在 B基因组或在 D基因组上 ,Bar基因的转移有很大差别。位于 B基因组上 Bar基因向联合山羊草转移比位于 D基因组上的 Bar基因更为困难。因为小麦基因组构成为 AABBDD,联合山羊草为 CCDD,它们有公共的 D基因组 ,在配子形成时 D基因组的染色体不会形成单价体而丢失。试验中 ,( 71系×联合山羊草 )×联合山羊草群体中 Bar基因抗性植株比例较高 ,( 3 1系×联合山羊草 )×联合山羊草未检出抗性植株。因此 ,B或 A基因组带 Bar基因的转基因小麦可以用来控制杂草 ,以减轻抗性基因从转基因小麦中向联合山羊草转移的风险。

The risk assessment of Bar gene transfer from B and D genomes of transformed wheat lines to jointed goatgrass was done by investigating the seed set of hybrids of crosses and back crossess.Transformed Bobwhite 31 line with Bar gene in B genome,71 line with Bar gene in D genome and jointed goatgrass served as the parents.Three ways of pollination,including non emasculation and spontaneous pollination,emasculation and spontaneous pollination,and emasculation and artificial pollination were adopted in order to verify the effects to bar gene transfer under the different pollination conditions.By testing the ratio of resistant plants in backcross population the safety assessment to Bar gene locating on B genome and on D genome was done.The results showed that the seed set was very poor using the way of non emasculation and spontaneous pollination,actually no seed was obtained in this experiment,however,the hybrids were available under the condition of artificial pollination.As to Bar gene transfer there was significant difference between the gene loci in B genome and in D genome.The former was more difficult to be transferred from transformed wheat to jointed goatgrass than the later,because wheat consists of AABBDD genomes and jointed goatgrass is CCDD genomes,which share a common D genome,so the chromosomes of D genome will not become univalent and be lost in forming gamete.In this experiment,a higher ratio of resistant plants was found in population of (71 line×jointed goatgrass)×jointed goatgrass,and no resistant plants existed in the population of (31 line×jointed goatgrass)×jointed goatgrass.Therefore the transformed wheat with Bar gene in B or A genome can be used to control grass in order to mitigate the risk of gene transfer from transformed wheat to jointed goatgrass.