Proton Gradient Regulator 5 of Gossypium arboreum Enhances Salt-Stress Tolerance in Gossypium hirsutum

Cotton is the most important cash and fibrous crop, and is grown in more than 50 countries of the world. Cotton crop yield is seriously affected by soil salinity. This deleterious effect can be reduced by genetic modification in stress-susceptible cotton plants. Salt stress tolerant gene gaPGR5 (proton gradient regulator 5) was isolated from Gossypium arboreum and transformed into the stress-susceptible cotton cultivar (G. hirsutum). The gaPGR5 gene was cloned into pCAMBIA- 1301 vector and transformed in young embryos by Agrobacterium-mediated method. Plant GUS gene was used as reporter gene that showed blue colouration during histochemical assay. Molecular analysis of transgenic plants was done up to T2 generation. Selection of salt-tolerant transgenic plants was done by salt-stress (NaCl) treatment with different concentrations in a hydroponic culture. Transgene expression in salt-tolerant transgenic plants was evaluated through quantitative real-time PCR. Maximum transgene expression was recorded in those plants which were tolerant to higher salt concentration (175 mM NaCl) and vice versa. The plants which give higher transgene expression against salt stress are valuable for cultivation in salt-affected areas.