Pollen Flow And Pollen-mediated Gene Flow Of Transgenic Wheat N12-1 With WYMV-Nib8 Gene

A variety of transgenic wheat has been successfully developed in the world, which some has been tested and evaluated in the field. When transgenic wheat is released into the environment for commercialization, the genes may escape from the transgenic wheat into the nontransgenic wheat varieties and its wild relatives, which might arouse serious concerns about biosafety. In particular, gene flow from the transgenic wheat into the nontransgenic wheat varieties may affect the seed purity and quality of the recipients, even cause the trade troubles between the countries and regions as well as the legal dispute, and if such seeds of traditional varieties were applied in farm, it could affect the genetic integrity of traditional varieties of germplasm resources.This paper regarded to transgenic wheat N12-1 with resistance to wheat yellow mosaic virus (WYMV) which developed in China, investigated the influences of wind direction, pollen source size and distance on pollen flow of transgenic wheat, and investigated the effects of pollen source size, pollen competitions and distance on pollen-mediated gene flow of transgenic wheat by controlled field cultivation experiments, The main results and conclusions of this work were described as follows:(1) The pollen flow frequencies dramatically reduced with the increase of the distance intervals between pollen donors and receivers. The results showed that most wheat pollen grains were mainly distrobuted within the distance of 5m.(2) The results showed that the pollen density of transgenic wheat reduced dramatically with the increase of distance from pollen sources in eight directions, while the significant difference in wheat pollen density showed in different directions.(3) The results showed that wheat pollen dispersal declined slowly with the increase of pollen source size within a given range. Because of the influence of wind speed and direction, there was an indirect proportion to relative pollen source size for pollen flow frequency, based on the exponential attenuation model. When the pollen density decayed to 0.001 grain/cm2 and 0.001 grain/cm2, the farthest distance of pollen flow was 16.32 m and 19.52 m among all treatments.(4) The gene flow frequencies dramatically reduced with the increase of the distance intervals between pollen donors and receivers, based on the exponential attenuation model, when the threshold of gene flow frequency set as 0.1% and 0.01%, the farthest distance of gene flow was 13.29 m and 17.01 m among all treatments. This indicated that isolation distance could be one of the effective ways to minimize pollen-mediated gene flow in the self-and wind-pollination crops.(5) There was no significant pollen size effect on the gene flow frequencies, gene flow frequency was no direct proportion to relative pollen source size, which might be ascribed to the dramatic reduction of pollen density along distance and the very low outcrossing rates in wheat varieties.(6) The pollen competitions with close spacing significantly affected the wheat gene flow and gene flow frequency, showing no direct proportion to relative pollen density.This investigation basically stated general trendence of the pollen flow and pollen-mediated gene flow in transgenic wheat, estimated the farthest distance of pollen flow and pollen-mediated gene flow in transgenic wheat based on the exponential attenuation model.