What is the basis of variation in stress tolerance in plants?

Abstract

The life cycle of plant, from seed germination, seedling growth, flowering to fruiting, depends on the suitable environment conditions. Plants have a remarkable capacity to occupy ecological niches that are shaped by their edaphic, climatic and biotic environments with extremes that have cyclic patterns, occur very infrequently or heterogeneously, or are chronic. Natural genetic variation for adaptation and acclimation mechanisms provide this inherent ecological niche capacity. To survive in an extreme environment, the growth pattern and flowering time of plants are changed by the organ evolution, even the life cycle, to adapt the special habitats. The evolved organs and living characteristics of these species also make the special habitats become their living environment for the reproduction and propagation. For adaptive phenotypic plasticity to evolve, individuals must be capable of responding to predictable environmental signals, and plastic genotypes must have a fitness advantage over genotypes that are incapable of altering their phenotypes. Plasticity in phenotypic traits can be heritable and subject to natural selection. One important feature distinguishing plants from other complex multicellular organisms is that plants are sessile and thus have to endure environmental challenges such as soil salinity, drought and cold temperatures. Water is an important component of living organisms, in addition to maintaining cell turgor, and metabolism of organism required. When plants suffer from drought stress, the reduction of photosynthesis is beneficial to reduce the damage of ROS to the cells. Photosynthetic metabolism in the chloroplasts of C3 plants applies highly cooperative regulation to minimize the fluctuation of metabolite concentration profiles in the face of transient perturbations. Highly cooperative regulation assures the robustness of the biological system and that there is closer cooperation under perturbation conditions than under normal conditions. Minimizing fluctuations in the profiles of metabolite concentrations is the key to maintaining a system's function. Although salt, water and cold stresses are clearly different from each other in their physical nature and each elicits specific plant responses, they also activate some common reactions in plants. The most widely studied common response is the induction of some plant genes by environmental stresses. Plant research dedicated to the understanding of mechanisms allowing plant to adjust to environmental constraints is amongst the most significant research domains both in quantity and quality. Plants provide unique opportunities to study the mechanistic basis and evolutionary processes of adaptation to diverse environmental conditions. Though various abiotic stresses negatively impact plant growth and productivity of crops, plants have adapted to respond to these stresses at the molecular, cellular, physiological, and biochemical level, enabling them to survive. Understanding stress signaling and responses will increase our ability to improve stress resistance in crops to achieve agricultural sustainability and food security for a growing world population.