Genetic Engineering of Cultivated Plants for Enhanced Abiotic Stress Tolerance

It is generally acknowledged abiotic stress tolerance is induced in response to an environmental stimulus resulting in the upregulation of multiple stress genes. Stimulus perception governs the extent of upregulation of stress associated proteins. This upregulation dictates when a plant initiates acclimation and thus the extent of stress tolerance the plant acquires. Often cultivated crops do not perceive an environmental stress, such as an episodic frost, early enough to acclimate. As a result, cultivated crops are often lethally injured by an unseasonal -3 to -4 °C frost whereas if given sufficient time they can acclimate to withstand much lower temperatures (e.g. -9 to -12 °C). Drought tolerance is generally induced as a consequence of plants experiencing a wet-dry cycle. During the day, plants lose turgor due to a water shortage; however, during the night plants regain turgor due to the reduced evapo-transpiration rate. As a result of the cycle, drought associated genes are upregulated. In many cool season crops, leaf temperatures exceeding 30 °C induce the formation of heat shock proteins that protect the cell. Maximum frost and drought tolerance is attained after several weeks of acclimating conditions; in contrast, enhanced heat tolerance can be attained in hours.