Salinity Stress Decreased Toxin Protein Content In Detached Leaf of Bt Cotton

Responses of two transgenic Bacillus thuringiensis (Bt) cotton (Gossypium hirsutum L.) cultivars, Newcotton 99B (99B) and Lumianyan-21(LMY-21), to 0, 50, 100 and 200mM NaCl stress were studied in growth chamber. All the content of potassium, sodium, soluble protein and free amino acid in the detached seedling leaves of two cultivars were increased with NaCl concentration increasing. Under 200mM NaCl, the content of potassium, sodium, soluble protein and free amino acid was increased by 474.5%, 5996.8%, 11.5%, 446.2% in leaves of 99B, and was increased by 11.9%,6819.5%,2.5%,48.3% in leaves of LMY-21, respectively. The content of Bt toxin protein were significantly decreased by salinity stress in two cultivars. In leaves of 99B and LMY-21, toxin protein was decreased by  26.5%,13.3 % under 50mM NaCl, 38.2%, 20.0 % under 100mM NaCl, 52.9 % , 16.7% under 200mM NaCl. The total N contents in leaves were decrease by NaCl treatment too. Condensed tannin content was increased by 100 mM NaCl, but decreased by 50 and 200 mM NaCl in leaves. The insect resistance of Bt cotton maybe affected under salinity field.