The Fitness Analysis On Hybrids Generated By Gene Flow From Transgenic Rice To Common Wild Rice(Oryza Rufipogon)

Common wild rice(Oryza rufipogon),known as the ancestor of cultivated rice(Oryza sativa),formed the extremely abundant genetic diversity during the long process of evolution.Wild rice contains all kinds of superior genes,is the huge resource for rice-breeding.Because of the high rate of natural hybrid and having the same genome AA,it is easy for common wild rice and cultivated rice to occur gene flow through pollen transmission.The transgene offspring are hybrids that produced by gene flow from transgenic rice to wild rice.It is important to study the characteristics of transgenes with the change of generation,its growth in the wild rice group,and the environmental adaptability of transgene offspring after the transgene go into the common wild rice group.Thus,to study the morphological and phenological characters of hybrids under the different environmental condition and know more about the changing law of them is conducive to assess the influence of the transgene to wild relatives by gene flow.The materials of this study were common wild rice in Hainan and its F1 hybrids with transgenic rice(hereafter referred to F1 hybrids).The plant height,tillers,leaf area,the content of soluble sugar,proline and other index of correlation were measured to analysis the influence of water depth and soil pH on the adaptability of common wild rice and F1 hybrids.Here are the research results:(1)Under the condition of soil moisture(as water depth was 0 cm),the growth advantage of F1 hybrids was dominant,and when water depth was 5 to 10 cm,common wild rice had greater advantage.The significant difference was found in leaf area between common wild rice and F1 hybrids.The leaf area of F1 hybrids was significantly greater than common wild rice respectively;(2)Under the condition of 10 to 20 cm water depth,the variety of physiological and biochemical metabolism in F1 hybrids was greatly suppressed by environmental stress.The soluble sugar content was low,content of MDA was high,and activity of CAT and POD were high,these can effectively reduce the survival competitiveness of F1 hybrids.Under the condition of 0 to 5 cm water depth,these physiological indexes of common wild rice were mostly not as good as F1 hybrids,and it was not conducive to wild rice to survive.(3)There were no significant effects of single soil pH treatment on the survival competitiveness of F1 hybrids.With 10 cm water depth in continuous irrigation with partial acid or alkaline soil can achieve the purpose of competitive advantage weakened of the F1 hybrids.Under this condition,stem,leaf and sheath dry weight of F1 hybrids were significantly reduced,tiller number was lower than the wild rice,proline content and POD activity were at a higher level,the growth of F1 hybrids was inhibited.(4)The two kinds of F1 hybrids seed had no dormancy.The dormancy of Wanning wild rice(A)was weak and the dormancy of Dongfang wild rice(B)was the strongest.The treatment of seed soaking with GA,seed soaking with nitric acid and dehulling all could break seed dormancy,and the effect of dehulling was the best.(5)The Plant height,panicle weight,population density and biomass of common wild rice in deep water levels(20-30 cm)treatments were significantly higher than that of shallow water treatments(p<0.05).Comparing the biomass and other indexes of common wild rice and weeds under different water depth,it was indicated that the water depth of 20 cm is the best for the common wild rice population.In conclusion,in similar deep-water environment in the simulated in-situ conservation of common wild rice,compared with common wild rice,transgenic rice and F1 hybrids had no survival advantage;The changes of soil pH had no significant impact on the survival competitiveness of F1 hybrids,but the partial acid or alkaline soil with continuous irrigation 10 cm water depth,can weaken the survival competitiveness of F1 hybrids.