Risk assessment of bar gene transfer from B and D genomes of transformed wheat (Triticum aestivum) lines to jointed goatgrass (Aegilops cylindrica)
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.