Fitness of Hybrids between Gossypium barbadense and Upland Cotton and Resistance to Pectinophora gossypiella and Alabama argillacea

Measuring fitness is essential for understanding the potential impacts of hybridisation between transgenic crops and their wild relatives. Transgenic CrylAc cotton Gossypium hirsutum and G. barbadense hybridise, the latter being valued as backyard cotton and an important genetic resource. G. barbadense was outcrossed to G. hirsutum containing the gene CrylAc and the isoline and the offspring evaluated for fitness as a measure of resistance to common pests and other growth parameters, Resistance to Pectinophora gossypiella and Alabama argillacea were greater in transgenic plants. Number of seeds per plant was higher in the F1 hybrids and G. hirsutum, F2 populations were intermediary; G. barbadense produced the least seeds per plant during the period of analysis. Anthesis of the first flower and opening of the first boll occurred earlier for G. hirsutum and Ft hybrids than F2; latest for G. barbadense. The observed-performance of resistance to the worms in the hybrids suggests that among FI and F2 populations transgenic hybrids may exhibit a competitive advantage over non-transgenic plants as a result of gene flow.