Mechanistic insights and future perspectives of drought stress management in staple crops

Abstract

Due to extended periods of below-normal rainfall and rising temperatures, drought is a significant global issue for agricultural productivity. Hydrological, agricultural, and meteorological droughts all pose different problems with regard to the availability of water for important crops, which in turn impacts plant development and yield. Depending on the crop species and stage of maturity, drought stress degrades plant metabolism and physiological processes, resulting in decreased growth and yield losses that can range from 30% to 90%. Acclimatization and adaptation are the two basic techniques that plants use to survive drought. Rapid alterations in physiological processes and chemical composition, including modifications to osmotic pressure, root and leaf size, and antioxidant systems, are all part of acclimatization. Xerophytism and succulence are two characteristics that drought-resistant plants have evolved to assist preserve cellular integrity and water balance in water-limited environments. Even with these tactics, the majority of important crops-such as maize, rice, and wheat-remain extremely vulnerable to drought stress. To lessen the effects of drought, researchers have looked into a number of strategies, including both conventional and cutting-edge methods. Conventional techniques, like the application of plant growth-promoting bacteria (PGPB) and morphological modifications, remain essential for improving drought resilience. Recent breakthroughs have provided innovative alternatives such as nanoparticle (NP) treatments and biochar, which enhance plant resilience. Biochar enhances soil moisture retention and nutrient accessibility, whereas nanoparticles augment water absorption and bolster molecular resilience under stress. Furthermore, microbial inoculants such as plant growth-promoting bacteria (PGPB) enhance nutrient and water absorption, facilitating growth in arid conditions. This review examines the impacts of drought stress on three important staple crops, emphasizing both traditional and novel approaches to lessen the consequences of drought. We highlight how combining insights from ecology, biochemistry, molecular biology, and cutting-edge technologies like biochar and nanoparticles can boost agricultural production and plant resistance in water-scarce environments.

Keywords: PGPB; drought stress; hormones; major staple crops; nanoparticles; osmolytes; sustainable solutions.

Figure 1

Negative effects of drought stress on the morphological, biochemical and environmental attributes of staple crops as well as soil. Drought stress effect both the physicochemical attributes of plants and soil which leads to decrease in growth and yield.

Figure 2

Different naturally built-in mechanisms in plants to overcome drought stress; physiological, biochemical and molecular responses. Plants have naturally building systems which help to prevent the plants from the negative effect of the drought.

Figure 3

Molecular pathways adopted at the cellular level to overcome drought stress and their activation by different amendments. The signal transduction process involves various enzymes, including kinases and phosphatases. Important enzymes include the mitogen-activated protein kinase (MAPK) cascade, calcium-dependent protein kinases (CDPKs), protein tyrosine phosphatases/dual specificity phosphatases (PTPs/DSPs), phosphoprotein phosphatases (PPPs), and type 2C protein phosphatases (PP2Cs). These signal transmissions cause metabolic responses, such as the production of antioxidants, chaperones, osmoprotectants, and proteins, that increase the ability of plants to handle drought stress. Transcription factors, including NAC, bZIP, WRKY, MYB, and AB2/ERF, play a role in enhancing the ability of plants to recover from drought stress by regulating gene expression in the nucleus.

Figure 4

A detailed pathway and activation of enzymatic and nonenzymatic components of antioxidants to mitigate oxidative stress in staple crops under drought conditions. Different enzymes are involved in the pathway, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione peroxidase (GPX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), reduced glutathione (GSH), and glutathione disulfide (GSSH).

Figure 5

Strategic amendments to combat drought stress in staple crops: improving growth and tolerance.

Figure 6

Nanoparticles (NPs) infiltrate plants through stomata, cuticles, lenticules, wounds, and the root system to staple crops under drought conditions. These NPs affect the generation of reactive oxygen species (ROS) within plant cells. To counteract the buildup of reactive oxygen species (ROS), the activation of antioxidant mechanisms is necessary. Key enzymes such as ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), glutathione reductase (GR), and monodehydroascorbate reductase (MDHA) play a part in these processes. This leads to a decrease in oxidative stress inside the mitochondria, facilitates effective photosynthesis, and improves drought tolerance.