Adaptation of Sorghum to Salinity Stress: A Mini Review

摘要

Plant salt stress resistance is the inherent ability of plants to withstand the effect of high salt concentrations in the root zone or on the leaves without a significant adverse effect. On the other hand plant salt tolerance is the ability of the plants to grow and complete its life cycle on a substrate that contains high concentrations of soluble salt. The reaction to salt stress varies with the stage of plant development. A given cultivar may be tolerant at one stage, but sensitive to another. Adaptation as a whole is defined as the long-term response during which the plant adjusts its physiology to the environmental conditions. Two types of response coexist in sorghum seedlings after pretreatment with NaCl, an adaptation response in which NaCl tolerance is increased, and a resistance response in which plant copes up with the salinity without modification of its tolerance level. Although salt-adaptation seems to be a widespread property of plants, the adaptive response has been rarely differentiated to the tolerance response. The induction of adaptation in Sorghum bicolor was only possible during specific time periods, called developmental windows. The period of exposure of the plants to non-lethal salinity apparently triggered a transient sensitivity to Abscisic acid and coincides with an increase in leaf Phospho Enol Pyruvate carboxylase activity which seems to occur faster if the plants are treated with ABA. The period during which developmentally perturbed leaf occur coincides with the period of induction of adaptation to high salinity suggesting the response may be used as a morphological marker of the adaptation process. The triggering activity of NaCl for adaptation to a whole range of environmental perturbations suggests that adaptation to salinity is not a pre-programmed response of the plants, but relates to learning processes occurring in animals. Adaptive modifications are transmitted to the progeny through maternal imprinting in the absence of natural selection. Adaptive response to salinity in showing variation in largenumber of sorghum genotypes reveals the role of change in the level of chromosome endoreduplication and intragenotype variation response.