Submitted to: Plant Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/26/2000
Publication Date: N/A
Citation: Interpretive Summary: Red rice is one of the most devastating weeds of rice and is made even more dangerous because it is capable of interbreeding with rice. Some varieties of rice recently have been altered genetically ('transformed' into 'transgenic' varieties) to be resistant to glufosinate, a herbicide that controls red rice. Field studies were conducted in 1997 in Louisiana and Arkansas to simulate the reproductive and plant vigor consequences of an unintended transfer of glufosinate resistance from glufosinate-resistant (transgenic) rice lines to red rice. Hybrid seeds used in these studies were produced from controlled crosses of either glufosinate-resistant or non-resistant rice lines and several red rice biotypes. Plant vigor and density, and seed dormancy and production at both locations were similar when the hybrids were developed from either transgenic or non-transgenic rice parents. Some differences in height and maturity in Louisiana were observed between hybrids from the two parental types, but these characteristics were not dramatically greater than in the original red rice parents, indicating that the weediness of the transgenic hybrids should be no greater than for non transgenic hybrids. The glufosinate resistance characteristics was inherited as a simple dominant trait in nearly half of the populations evaluated. These results suggest that location or environmental factors may affect to varying degrees the reproductive and plant vigor consequences of hybrids arising from unintended crosses between glufosinate-resistant rice and red rice.
Technical Abstract: The genetic and agronomic consequences of transferring glufosinate (Liberty TM) herbicide resistance from transgenic rice (Oryza sativa L.) lines to the noxious weed red rice (Oryza sativa L.) were evaluated under field conditions. Replicated field trails in Louisiana (LA) and Arkansas (AR) were conducted in 1997 to evaluate ten vegetative and reproductive traits of eight F2 populations produced from controlled crosses of two transgenic glufosinate-resistant rice lines and four red rice biotypes. Plant vigor and plant density at both locations were similar among populations derived from either transgenic or non-transgenic parents. Significant differences in plant height and maturity were observed among LA populations produced from transgenic lines when compared to corresponding populations developed from non-transgenic material. However, values for these traits were not greater than those detected in the red rice biotypes. Seed dormancy and seed production were not significantly different at either location among transgenic and non-transgenic populations. Dominant Mendelian segregation of glufosinate resistance was detected in 40% of the populations evaluated. Results of this study indicated that those populations segregating for glufosinate resistance responded in a location-specific manner with respect to life history and fecundity traits.