FITNESS OF INTERSPECIFIC HYBRIDS IN THE GENUS SORGHUM - PERSISTENCE OF CROP GENES IN WILD POPULATIONS

Gene Bow can be expected to occur in many crop/weed complexes if the c rop and the weed have sympatric ranges, are sexually compatible, have flowering times that overlap, and share a common pollinator. These con ditions are met in a large number of crop/weed complexes; however, the consequences of gene exchange between crops and wild relatives on a w ide scale, and the potential fate of escaped engineered genes, remain generally unknown. It is believed that an examination of the fitness o f weed/crop hybrids will provide insight into the potential fate of ge netically engineered genes, or transgenes, in the wild. We examined se veral fitness correlates of weed X crop hybrids between crop sorghum a nd a related noxious weed, johnsongrass. Comparisons were made with no nhybrid johnsongrass under agricultural conditions, Hybrid weeds did n ot show any significant increase or decrease in time to flowering, pan icle production, seed production, pollen viability, tiller production, or biomass. We conclude that a transgene that is either neutral or be neficial to johnsongrass would likely persist in populations growing i n agricultural conditions under continued gene Bow from the crop.