**2. Drought stress effects on agricultural production**

In nature, plants are exposed to various environmental stresses due to their sessile lifestyle. These different unfavorable factors negatively impact plant growth, productivity, and their geographic distribution. Plants may face many diverse stresses (e.g., drought, salinity, and pathogens) under field conditions individually or in combination, which might have a devastating effect on crop yield [10]. Water is the most essential resource for plants, and all the plant organs need to maintain 60–90% water content for sustainable activity. However, global climate change, caused by different anthropogenic activities and greenhouse gas emissions, has become more thoughtful worldwide, leading to drought conditions all over the world [11]. In agricultural technology, it is considered one of the main environmental stresses for plants. Due to the frequent changes in climate observed throughout the world, it has increased the severity of drought events for plants [12]. Important cereal crops are increasingly diminishing by over 10% yield due to drought stress, and it is still the main limiting factor of food production in numerous countries [13]. Decrease in plant metabolism and electrolyte disturbances in plant cells are major symptoms of drought stress, which automatically lead to their death. Because of inhibiting various morphological, physiological, and biochemical processes such as changes in leaf, root length, biomass photosynthesis, respiration, translocation, carbohydrate synthesis, nutrient metabolism, ion uptake, and growth promoters of plants are affected [14]. Also, it primarily prevents the photosynthesis system by causing an imbalance between light capture and utilization, due to which Rubisco activity is reduced and the amount of photosynthetic pigments, inhibiting leaf area and damaging the photosynthetic apparatus [15]. Similarly, it reduces the rate of carbon fixation by inhibiting metabolism or limiting carbon dioxide input into leaves. It also leads to various biochemical changes, such as an excessive accumulation of ROS including O2−, and H2 O2 , inside the host, which can further damage various tissues and cellular constituents such as nucleic acids and other biomolecules, resulting in cell death [16]. Furthermore, drought also lowers seedling vigor and affects germination by reducing water intake. Wilting, yellowing, discoloration, and leaf burning are the phenotypic signs observed in plants under drought condition [17]. Also, leaf senescence, drooping, leaf rolling, brittleness, scorching, limp leaves, premature fall, etiolation,

wilting, turgidity, flower sagging are the other symptoms observed [18]. Drought stress also alters carbon permeability and transport networks by lowering cation (Ca2+, K+ , and Mg2+) absorption by roots. They later can also limit development by preventing the activity of several critical enzymes that take part in nutrient digestion, uptake, translocation, and metabolism of plants [19]. It also has a negative impact on biogeochemical cycles, such as the nitrogen and carbon cycles, which further reduce the decomposition of organic matter that considerably lowers the uptake of water and minerals by the root system, thus increasing soil fertility. For instance, many droughttriggered plants decreasing in macronutrient absorption and translocation (K, N, and P) are found [20]. Many vital characteristics representing plant water relations in plants include relative water content (RWC), leaf water potential, stomatal conductance, transpiration rate, leaf, and canopy temperatures [21]. These traits have also been found to be affected considerably during drought stress in plants [22]. So the above information shows that water scarcity affects plants at all growth stages but causes maximum damage during critical growth phases, such as during the seed development stage or reproductive phase, thereby reducing seed size, number, and quality, which are primarily responsible for substantial yield losses [23].

### **3. Potential strategies to mitigate drought stress in plants**

Plants incorporate a wide range of morphological, physiological, and molecular defense responses contrary to drought, which prevents water loss, maintaining cellular water content, and water supply to vital parts [24]. Drought stress can be reduced through breeding, mass screening, and exogenous phytohormone production. Different strategies are used by plants to minimize stress, for example, by producing phytohormones (e.g., abscisic acid (ABA) and gibberellins) and low-molecular-weight osmolytes (e.g., amino acids and polyols) and by modifying succulent leaves to reduce transpiration loss [25]. Also, a significant plant defense strategy in response to drought is the transcriptional and translational reprogramming of key genes and proteins that are involved in signal perception and transduction, transcription factors, and upregulation of drought tolerant genes, all of which drive drought resilience [26]. Plants protect themselves from droughtinduced reactive oxygen species (ROS) and other radicals owing to their efficient antioxidant system. During extended drought stress, they also synthesize an array of osmoprotectants such as prolines, soluble sugars, betaine, and spermines, to maintain cell turgor pressure. Over the past two decades, researchers have focused on transgenic approaches and other molecular breeding tools to increase drought resilience in different crops [27]. For instance, various biotechnological tools, such as CRISPR/Cas, RNAi, and transgenics, have made significant contributions to improving drought-resilient traits in both model and crop plants. But due to their high costs, complexity, ethical considerations, and toxicity concerns, their accessibility to farmers has been limited [27]. Furthermore, adaptive responses in plants are driven by complex genetic features involving several pathways, which have proven to be major impediments to long-term drought-tolerant crop improvement. Furthermore, the development of climate-resilient crops is required by integrating modern technological methods. The use of next-generation breeding approaches (genomic selection and genomic editing) and high-throughput phenotyping is desirable to develop crops that are exposed to different stresses [28]. Also, different bioinformatics tools have also been reported to overcome stress responses [29].

*Microbial Mitigation of Drought Stress in Plants: Adaptations to Climate Change DOI: http://dx.doi.org/10.5772/intechopen.109669*

The recent advancement in genomics and genome editing technologies has been coming across various approaches of genetic study to produce climate-resilient crops [30]. Many other strategies are incorporated to grow climate-resilient/smart crop including SNP genotype, trait mapping, and plant breeding methods. The CRISPR/ Cas technology has also been efficiently used in enhancing productivity in rice crop in fluctuating climatic conditions [31].
