Expression of S-adenosyl methionine decarboxylase gene for polyamine accumulation in Egyptian cotton Giza 88 and Giza 90.

Developing drought tolerance in Egyptian cotton varieties is a strategic goal considering the need to expand cotton cultivated area and water scarcity in the Nile valley. In the present study, increasing levels of polyamine accumulation via expressing S-adenosyl methionine decarboxylase (SAMDC) gene was the main goal. SAMDC cDNA isolated from Saccharomyces cerevisiae isolate was isolated and genetically engineered into Egyptian cotton varieties Giza 88 as an extra long staple and Giza 90 as a long staple by means of particle bombardment through meristem transformation.T(0) transgenic plants were screened using basta herbicide (200 mg/l). RT- PCR analysis was used to confirm gene expression while gene integration was confirmed by Southern blot analysis. Control plants from Giza 88 and Giza 90 were subjected to drought regime using different concentrations of PEG 6000 (2.5%, 5%, 7.5%, 10%, 12.5%, 15%, 17%, and 20%) for 9 hrs to record drought stress symptoms and determine the potential concentration level for inducing polyamine accumulation. 17% of PEG 6000 was considered the sublethal concentration showing drought stress symptoms and therefore was used as potential stress concentration for estimating the level for spermine accumulation in both control and transgenic Giza varieties. T(1) transgenic plants grown under induced drought stress regime were tested positive for gene integration and expression and subjected to HPLC analysis to determine levels of spermine as polyamine accumulated compound in response to drought stress regime. Elevated spermine accumulation in Egyptian cotton varieties Giza 88 and Giza 90, were compared as non transgenic plants grown under same induced drought conditions with T(1) transgenic plants using reverse-phase HPLC analysis. Elevated spermine accumulation expressing SAMDC gene reflect main cause for increasing drought tolerance in both transgenic varieties.