Safety Assesment On Potential Weediness Of Glufosinate-Resistant Transgenic Rice And Gene Flow From Transgenic Rice To Weedy Rice

Large-scale environmental trials and commercial release of herbicide-resistant transgenic rice may bring environmental biosafety issues. One of the main concerns regarding the release of transgenic herbicide-resistant (HR) rice is, weediness of HR rice, the other one is gene flow through pollen dispersal to weedy rice Therefore, it is important to assess potential risk on weediness and gene flow of HR rice before its commercial release. In order to provide information on potential weediness and gene flow and of HR rice II you86B. its transgenic restorer86B, and HR rice125S/Bar68-1, the potential weediness of transgenic restorer86B and potential transgene flow from HR II you86B, transgenic restorer86B, and HR rice125S/Bar68-1to weedy rice were assessed in field. The main results were as follow:1Potential risk assessment on Weediness of Transgenic Glufosinate-Resistant Rice b86BThe surviving and reproduction ability, seed shattering, seed viability of transgenic glufosinate-resistant rice86B, recipient variety and conventional rice variety shanyou63were comparatively evaluated in the field, and tolerance of three rice varieties to flucetosulfuron was also observed in greenhouse. The surviving and reproducing ability of transgenic rice and recipient rice were less than that of conventional rice variety no matter in appropriate season or in unfavorable season, especially in unfavorable season. Transgenic rice variety showed a little bit less on plant height, tiller number and production than recipient ones. Therefore it was demonstrated that transgenic rice variety was demonstrated lowest on surviving and reproducing ability among the three ones. The seed shattering of the three rice varieties were weak, and no volunteer seedlings were found in experimental season. Under the shallow and the deep buried, the seed viability of transgenic rice was weaker than that of conventional rice and recipient rice. The tolerance of three rice varieties to herbicides flucetosulfuron was similar. It is concluded that potential weediness of the transgenic glufosinate-resistant rice86B was low in Nanjing, China.2The gene flow from glufosinate-resistant transgenic rice86B Ⅱ and86B to3populations of weedy riceThe HR rice86B II or86B as the pollen donor and weedy rice (from Dandong, Taizhou, Zhaoqin) as recipients were planted interlacedly in the field. The synchronous flowering of HR rice and weedy irce were observed.And gene flow rate were measured. The flowering time of Taizhou weedy rice under transplanting condition,and zhaoqin weedy rice under direct seeding condition met with that of86B II.,The outcrossing rate from86B II to Taizhou weedy rice and zhaoqin weedy rice was1.36%oand0.18%o respectively. The flowering time of other weedy rice under transplanting or direct seeding condition didn’t met with86B II..Under direct seeding, the flowering of Zhaoqin weedy rice met with that of86B, and the outcrossing was0.16%o. The flowering time of other weedy rice under transplanting or direct seeding condition didn’t met with86B..The results showed that there were a potential gene flow from HR Ⅱ86B to Zhaoqing and Taizhouweedy rice and86B to Zhaoqin. Therefore potential gene flow from II86B and86B to Zhaoqin and Taizhou weedy rcie should not be ignored.3The gene flow from glufosinate-resistant transgenic Xiang125S/Bar68-1to7populations of weedy rice and lvariety of conventional riceThe gene from from glufosinate-resistant transgenicXiang125S/Bar68-1to7populations of weedy rice (from Shenyang, Panjin, Anhui, Hunan, Zhaoqing, Taizhou, Guangxi) and conventional rice204was assessed in close condition in field. The Outcrossing rates from transgenic rice to7biotypes of weedy rice were tested. The results demonstrated that Outcrossing rate from HR rice to Hunan weedy rice was1.869%o, which was highest, in this experiment. However outcrossing rate from HR rice to Guangxi weedy rice was0. Outcrossing rate from HR rice to conventional rice204was0.604%o. It was concluded that the risk of gene flow from HR rice Xiang125S/Bar68-1to the most populations of weedy rice should not be ignored.