Gene Flow from transgenic rice to red rice (Oryza sativa L.) in the field

In this study, we simulate a transgenic rice crop highly infested with red rice to examine\r\ntransgene transfer from a transgenic line (A2504) resistant to glufosinate ammonium\r\nto cohabitant red rice. The red rice was sown along with the transgenic line at\r\nthe highest density found in naturally infested crops in the region. Agricultural practices\r\nsimilar to those used to control red rice infestation in northern Italy rice fields\r\nwere used to reproduce the local rice production system. During the first 2 years, the\r\nfield was treated with herbicide at the appropriate time; in the first year the dosage of\r\nherbicide was three times the recommended amount. In this first year, detectable red\r\nrice plants that escaped herbicide treatment were manually removed. Nevertheless,\r\ntwo herbicide-resistant hybrid plants (named 101 and 104) were identified in the\r\nexperimental field during the second year of cultivation. Phenotypic and molecular\r\ncharacterisation suggests the hybrid nature of these two plants, deriving from crossing\r\nevents involving A2504, respectively, with red rice (plant 101) and the buffer cultivar\r\nGladio (plant 104). The progeny of two subsequent generations of the two plants were\r\nexamined and the presence of the transgene detected, indicating stable transfer of the\r\ntransgene across generations. In conclusion, despite control methods, red rice progeny\r\ntolerant to the herbicide can be expected following use of transgenic rice and, consequently,\r\ndifficulties in controlling this weed with chemicals will emerge in a relatively\r\nshort time.