Asparaginase over-Expressing Cotton (Gossypium hirsutum L.) Plants Show Reduced Protein Content in Embryos

Asparaginase over-expressing cotton transgenic plants were generated, via Agrobacterium tumefaciens (LBA4404 strain) mediated genetic transformation of Gossypium hirsutum cv. Coker 312, with seed-specific- or CaMV35S-promoter-driven gene constructs. Primary transgenic plants, resistant to kanamycin on MSM plant growth media, were characterized by PCR with asparaginase gene specific primers and grown to maturity in greenhouse. T1 and T2 cotton seeds, engineered to over-express asparaginase, were harvested from greenhouse grown plants. Transgenic seeds subjected to non-destructive TD-NMR method of protein and oil content analysis showed markedly reduced protein content down to 15% by weight (from ~22-23% in the Coker 312 non transgenic background). No changes in total oil content were recorded. Reduction in seed storage protein appears to be at the expense of seed mass. Photosynthesis rate measurements/CO2 exchange rate using a Li Cor 6400XT System (portable) were done to elucidate any real time relationship between seed reserve accumulation and photosynthesis rate. Comparative analysis of yield showed superior performance of asparaginase over-expressers over non-transgenic Coker 312 plants.