Extremophiles Adaptation and Its Utilization in Mitigating Abiotic Stress in Crops

Several studies have shown that biotic and abiotic factors are among the major causes of reduced crop yield globally. Scientists are predicting that environmental changes will cause more pressure on crops in the form of heavy rains and floods, extreme heat waves, and ultra-low temperatures as well as longer periods of drought conditions in the near future. To combat such abiotic stress conditions, plants require efficient and rapid adaptation to become more tolerant. Improved breeding methods and efficient resource management have been successful to some extent, enabling plants to tolerate abiotic stress conditions. Microorganisms inhabit a wide range of niches that are generally stressful for crop plants. Recent studies indicate that such microorganisms have enormous metabolic capabilities and can be utilized as tools for making crops stress-resilient. Extremophiles have evolved specialized gene regulatory mechanisms which enable them to express stress-responsive genes to survive in extreme conditions. Microorganisms have a long-standing co-evolving relationship with plants, assisting each other in modulating local and systemic mechanisms that provide defense against extreme environments. Understanding of these complex and integrated processes is becoming increasingly evident as the molecular, biochemical, and physiological insights are being explored at cellular levels. Looking at the rapidly changing climate conditions, such abiotic-stress-responsive plant–microbe interactions have become more imperative. These unique properties of extremophiles, such as their ubiquitous presence, extreme environment tolerance capabilities, and genetic diversity, could be exploited to generate crops which can cope with abiotic stresses more efficiently. Extremophiles can interact with the crop plants in the rhizosphere and make biofilm and produce polysaccharides which can influence its physicochemical properties as well as provide tolerance against multiple abiotic stress conditions via mechanisms like osmo-protectant induction and production of heat shock proteins (HSPs) in plant cells. Being an excellent model, molecular insight in extremophiles can provide tools to engineer crop plants to be tolerant to extreme environments. Although there are enormous varieties of microorganisms that share symbiotic relationships with plants, this phenomenon with extremophiles is less explored. Therefore, this holds great potential in identifying and designing novel tools that could be utilized for developing crop varieties with robust stress-tolerant traits. In this chapter, we have discussed the different abiotic stresses and the mechanisms used by different extremophiles to alleviate these extreme conditions and their utilization for stress alleviation in crops.