Phytohormones Trigger Drought Tolerance in Crop Plants: Outlook and Future Perspectives

Abstract

In the past and present, human activities have been involved in triggering global warming, causing drought stresses that affect animals and plants. Plants are more defenseless against drought stress; and therefore, plant development and productive output are decreased. To decrease the effect of drought stress on plants, it is crucial to establish a plant feedback mechanism of resistance to drought. The drought reflex mechanisms include the physical stature physiology and biochemical, cellular, and molecular-based processes. Briefly, improving the root system, leaf structure, osmotic-balance, comparative water contents and stomatal adjustment are considered as most prominent features against drought resistance in crop plants. In addition, the signal transduction pathway and reactive clearance of oxygen are crucial mechanisms for coping with drought stress via calcium and phytohormones such as abscisic acid, salicylic acid, jasmonic acid, auxin, gibberellin, ethylene, brassinosteroids and peptide molecules. Furthermore, microorganisms, such as fungal and bacterial organisms, play a vital role in increasing resistance against drought stress in plants. The number of characteristic loci, transgenic methods and the application of exogenous substances [nitric oxide, (C28H48O6) 24-epibrassinolide, proline, and glycine betaine] are also equally important for enhancing the drought resistance of plants. In a nutshell, the current review will mainly focus on the role of phytohormones and related mechanisms involved in drought tolerance in various crop plants.

Application of 2,4-Epibrassinolide Improves Drought Tolerance in Tobacco through Physiological and Biochemical Mechanisms

“…Plants respond to drought stress by accumulating different phytohormones, including BR and IAA. These hormones further trigger drought tolerance by regulating several biochemical and molecular processes [ 82 ]. Several attempts have been made to highlight the role of genes involved in cell expansion/cell elongation induced by IAA.…”

Variation in Root-Related Traits Is Associated With Water Uptake in Lagenaria siceraria Genotypes Under Water-Deficit Conditions

“…Drought is a compelling ecological issue that significantly damages plant development and growth (Fahad et al, 2017 ; Iqbal et al, 2022 ). In this sense, water scarcity has had a negative impact on crop yield, putting food security at risk in many drought-prone areas in the world (Ellsworth et al, 2020 ; Payus et al, 2020 ; Fahad et al, 2021a , b , c ).…”

“…Therefore, in order to enhance the sustainability of agriculture, it is necessary to develop genotypes with high yields, water-use efficiency, and water productivity (WP). In response to drought stresses, plants have developed several physiological, phenological, morphological, and biochemical adaptation mechanisms in different plant organs (i.e., roots, stems, and leaves) to respond to severe water stress (Fahad et al, 2017 , 2021c , d , e , f ; Mashilo et al, 2018 ; Kamran et al, 2019 ; Zacarias Rafael et al, 2020 ; Iqbal et al, 2022 ). In particular, root system architecture (RSA) plays an important role in water extraction from the soil, especially in drought environments (Strock et al, 2019 ; Fahad et al, 2021b ).…”

“…In particular, root system architecture (RSA) plays an important role in water extraction from the soil, especially in drought environments (Strock et al, 2019 ; Fahad et al, 2021b ). Therefore, the identification and improvement of genotypes based on root traits have been of interest in crop breeding, mainly for the maintenance of crop productivity under water-deficit conditions (Lynch, 2018 ; Iqbal et al, 2022 ). Root system architecture traits are important drivers of many ecosystem processes, such as carbon and nutrient cycling, as well as the response to water-deficit episodes (Lynch, 2018 ; Lozano et al, 2020 ).…”

Rice Straw Vermicompost Enriched With Cellulolytic Microbes Ameliorate the Negative Effect of Drought in Wheat Through Modulating the Morpho-Physiological Attributes

“…Environmental stresses including elevated temperature, drought, heavy metals, salinity, and waterlogged conditions, negatively affect the morpho-physiological processes of plants, and thus the agronomical yield of agricultural crops (Hussain et al, 2020;Hussain et al, 2021;Naseer et al, 2021;Zahra et al, 2021;and Iqbal et al, 2022). Among these climatic factors, drought (also termed deficient precipitation) has emerged as one of the most threatening challenges due to climate change (Hussain et al, 2018;Hussain et al, 2019;Ahmad et al, 2021;and Mubarik et al, 2021).…”