Evaluation of Stability of Chitinase Gene in Transgenic Offspring of Cotton (Gossypium hirsutum)

Cotton cultivar Coker has been already transformed with recombinant pBI121-chi via Agrobacterium tumefaciens. The T-DNA region of pBI121-chi carries the chitinase (chi ) gene from bean and is under the control of the CaMV35S promoter. T1 and T2 progenies of transgenic cotton containing the chi gene were used in this study.  Polymerase chain reaction (PCR), Southern and Western blotting data confirmed integration and expression of the chi gene in the T1 and T2 progenies. The growth of Verticillium dahliae was singnificantly inhibited in an in vitro bioassay for which 100 μg of crude leaf protein extract derived from the T1 plants was used. The 850-bp expected chi fragment was amplified for 77 transgenic plants from 128 T1 and T2 progenies, and 75 transgenic plants showed both chi and nptII bands. T0 conduct bioassay, cotton seedlings were infected with the spore suspension (106 spores/ml), in a greenhouse. Fifty-five percent of the transgenic plants were able to restrict V. dahliae growth and symptoms. There were no distinguishable differences in the phenotypic appearance of transgenic plants compared to non-transgenics. These results showed that transgenic cotton expressing a bean chitinase exhibited enhanced resistance against  V. dahliae in greenhouse and in-vitro assay as compared to the non-transgenic plants.