Studies on Plant Responses to Abiotic Stresses: Under In-Vitro Conditions vs Natural Habitat

Abstract

In order to survive, plants must adapt to abiotic stress like drought, temperature, high- salinity etc. The study of plant responses to abiotic stress is one of the most active research thrust in plant biology, not only due to its indisputable academic interest, but also because of its practical implications in agriculture, since abiotic stress (mainly drought, high & low temperature and soil salinity) is the major cause for the reduction in crop yields worldwide. Studies on abiotic stress response in model systems, like in Arabidopsis, have only allowed to describe basic molecular mechanisms of stress responses viz. osmotic balance regulation, ion homeostasis, activation of antioxidant systems and protective metabolites synthesis, etc. However, in majority of cases, these responses, could not lead to abiotic stress tolerance. Indeed, like Arabidopsis, almost all the important crop plants are somewhat susceptible to abiotic stresses, while some specialized plants groups like halophytes, gypsophytes, xerophytes etc. are tolerant to drastic abiotic stress conditions in their natural habitats. Although, both tolerant and susceptible may share the same molecular response, Therefore, the mechanisms of response operating in stress tolerant taxa can be expected to be more effective than those of non-tolerant species. Consequently, comparative studies of genetically related, stress tolerant and stress sensitive naturally occurring species under natural habitat are gaining increasing attention because of their potential for understanding stress tolerance mechanisms. These quantitative differences might be dependent on, and modulated by the edafo-climatic properties and their spatial and temporal changes of the habitat, where plants develop. Therefore, the abiotic stress response studies on non-tolerant model under in-vitro conditions allows a stricter experimental control but do not reflect the natural atmosphere of the plants. Therefore, the studies on abiotic stress response of tolerant plants under their natural habitat may contribute to our understanding on abiotic stress tolerance mechanisms, providing complementary information to that obtained from more common studies with non-tolerant model species and laboratory or greenhouse artificial conditions.