Annon, Ali Hani Hamza (2012-10). Overexpression of Tobacco Osmotin Protein in Carrot (Daucus carota L.) to Enhance Drought Tolerance. Master's Thesis.
Thesis
Lack of water is one of the most significant issues that already threaten world agriculture as many countries are unable to meet the demand for water to grow the crops. To make matters worse, the water availability is expected to fall by half by 2050, thus severely restricting agriculture production. Genetic engineering of crops to enhance their tolerance to such unfavorable environment represents one of the few approaches that can help us address this problem. Osmotin and osmotin-like proteins are stress proteins, belonging to the plant PR-5 group of proteins, which induced in response to various types of biotic and abiotic stresses in several plant species. Carrot plants were transformed with tobacco osmotin gene that encodes a protein lacking 20 amino-acid sequence at the C terminal end under the control of CaMV 35S promoter using the Agrobacterium-mediated transformation method. The gene integration and expression were confirmed by Southern and Western blot analyses and the transgenic plants were evaluated for their ability to tolerate drought stress. Under drought conditions, transformants exhibited slower rates of wilting compared to the wild-type and gained the ability to recover faster than their untransformed counterparts when the drought stress was alleviated. Under water stress, transformants showed lower levels of H2O2 accumulation, reduced lipid peroxidation and electrolyte leakage, and higher leaf water content. Taken together with some earlier reports, our results provide additional evidence for the protective ability of tobacco osmotin protein against drought stress and suggest a possible means to achieve tolerance against a serious type of abiotic stress.
