Genetic and Molecular Characterization of OSMII Over-Expressing Transgenic Cotton (G. hirsutum L.) Plants

With the main objective of engineering cotton plants with improved tolerances to biotic and/or abiotic stresses, upland cotton (Gossypium hirsutum L. cv Coker 312) was engineered to consitutively overexpress one of its own inducible osmotin genes (OSMII). Osmotin or osmotin like proteins have been shown to provide protection against biotic and abiotic stresses in plants.  A modified method utilizing the cotton embryogenic cell lines and Agrobacterium-mediated transformation was used to generate four independent transgenic events. The coding sequence of Cotton OSMII (~800 bp) under the control of the CaMV 35S promoter was engineered into the Gateway binary vector, pMDC 32 and pMDC43, for transformation. Transgenic cells and embryos were selected on hygromycin and regenerated plants were transferred to the greenhouse for maturation and seed production. Transgenic T0 plants and T1 progeny derived from two independent fertile T0 transgenic lines, were confirmed as transgenic by PCR amplification of the transgene promoter sequence.  Genotyped transgenic T1 seedlings overexpressing OSMII were compared with non-transgenic Coker 312 seedlings for their tolerance to cotton aphids (Aphis gossypii). Preliminary experiments suggest that OSMII overexpression confers some tolerance to aphids, slowing their rate of reproduction.