Agrobacterium-mediated transformation of cotton (Gossypium hirsutum) using a heterologous bean chitinase gene

Cotton ( Gossypium hirsutum L., var. Coker 312) hypocotyl explants were transformed with three strains of Agrobacterium tumefaciens, LBA4404, EHA101 and C58, each harboring the recombinant binary vector pBI121 containing the chi gene insert and neomycin phosphotransferase (nptII) gene, as selectable marker. Inoculated tissue sections were placed onto cotton co-cultivation medium. Transformed calli were selected on MS medium containing 50 mg l(-1) kanamycin and 200 mg l(-1) cepotaxime. Putative calli were subsequently regenerated into cotton plantlets expressing both the kanamycin resistance gene and beta-glucuronidase (gus) as a reporter gene. Polymerase chain reaction was used to confirm the integration of chi and nptII transgenes in the T-1 plants genome. Integration of chi gene into the genome of putative transgenic was further confirmed by Southern blot analysis. 'Western' immunoblot analysis of leaves isolated from T-0 transformants and progeny plants (T-1) revealed the presence of an immunoreactive band with MW of approximately 31 kDa in transgenic cotton lines using anti-chitinase-I polyclonal anti-serum. Untransformed control and one transgenic line did not show such an immunoreactive band. Chitinase specific activity in leaf tissues of transgenic lines was several folds greater than that of untransformed cotton. Crude leaf extracts from transgenic lines showed in vitro inhibitory activity against Verticillium dahliae. Transgenic plants currently growing in a greenhouse and will be bioassayed for improved resistance against V. dahlia the causal against of verticilliosis in cotton.