Pollen-mediated herbicide-resistance transgene flow can occur through both direct transgene transfer and reverse weediness trait movement between transgenic rice and weedy rice. However, the latter potential risk has been seriously underestimated or even ignored in transgenic crop management.
Weed Research Laboratory of Nanjing Agricultural University recently research found the segregating progeny of transgenic hybrid rice pollinated by weedy rice can rapidly derive into weedy forms carrying the transgene. Six materials (two glufosinate-resistant transgenic rice varieties, twoglufosinate-resistant transgenic hybrid rice and its F2 generation) and their succeeding generations were planted for three years in weedy-rice-free field plots adjacent to experimental weedy rice fields.Weedy-rice-like (feral) plants, both glufosinate-resistant and with red-pericarp seed, were initially found only among the F3 generations of the two glufosinate-resistant transgenic hybrid rice. The composite fitness of feral progeny was significantly higher than glufosinate-resistant transgenic hybrid rice (the original female parent of feral progeny) under common garden conditions. Hybrid rice progeny segregated into individuals with variable height and extended flowering. In a separate gene flow experiment, hybrid rice F2 generations had significantly higher outcrossing rates than their progenitors. These suggest that herbicide-resistant weedy rice can rapidly arise by reverse pollen-mediated gene flow to transgenic hybrid rice whose segregating progeny, having a higher outcrossing ability, pose greater agro-ecologicalrisk than transgenic varieties.Herbicide-resistant transgenic hybrid rice requires stringent safety management practices both in its breeding and field production.
This research was published online by Journal of Experimental Botany in June 2018. The title of the article is “Feral rice from introgression of weedy rice genes into transgenic herbicide-resistant hybrid-rice progeny”(10.1093/jxb/ery210).