Advancing Drought and Salinity Stress Tolerance in Plants: Mechanisms, Molecular Tools and Breeding Strategies—A Review

Genetic and Molecular Mechanisms of Plant Stress Tolerance and Strategies for Improvement: A Comprehensive Review

Environmental stresses impose a significant threat on plant growth and agricultural productivity. Abiotic stresses, such as drought, salinity, and extreme temperatures, impair plant physiology and development, while biotic stresses, like those caused by pathogens and herbivores, trigger a range of defense responses. Plants have evolved intricate genetic and molecular mechanisms to cope with these challenges. The plant response to stress is governed by transcription factors (TFs), including the AP2/ERF, bZIP, WRKY, and NAC families, which regulate stress responsive gene expression. Phytohormones like ABA, ethylene, and jasmonic acid (JA) serve as crucial signaling molecules that initiate adaptive physiological changes. These signals are transmitted via signal transduction components, such as receptor-like kinases and MAP kinases, which translate external events into cellular responses. Additionally, epigenetic regulation and gene-by-environment (G × E) interactions allow plants to acquire a stress memory and exhibit adaptive plasticity, enhancing their resilience to future challenges. Improving these natural mechanisms is vital for developing stress-tolerant crops. Traditional breeding and modern techniques like Marker-Assisted Selection, Genetic Engineering, Genome Editing and Genomic Selection are used to identify and integrate desirable traits into new crop varieties. These methods enable breeders to develop more robust and stable crops, ultimately helping to ensure global food security in the face of climate change.

Negative regulators that mitigate abiotic stress sensitivity of rice: insights and future perspectives

Salinity signaling networks in wheat: crosstalk among Ca2⁺, ROS, phytohormones, and metabolic signals in salt adaptation

Abstract Soil salinity limits wheat productivity by disrupting water uptake, Na⁺/K⁺ homeostasis, photosynthesis, reproductive development, and grain filling. Although wheat salinity tolerance is often discussed in terms of individual traits such as Na⁺ exclusion, antioxidant defense, osmolyte accumulation, or abscisic acid signaling, these responses operate as interconnected signaling networks. This review reframes wheat salinity adaptation as a crosstalk-driven process linking early root perception with whole-plant acclimation and yield-related outcomes. At the root-soil interface, salinity rapidly lowers external water potential, alters membrane potential, disturbs ion fluxes, and induces early Ca2⁺, reactive oxygen species (ROS), pH, nitric oxide, electrical, and phosphorylation signals. Ca2⁺ sensors and decoders, including CaM/CMLs, CDPKs, and CBL-CIPK modules, connect these early signals with ROS regulation, ion-transporter activity, kinase cascades, and transcriptional reprogramming. ABA integrates osmotic stress with stomatal closure, hydraulic adjustment, compatible-solute accumulation, and water-use regulation, whereas additional hormonal and metabolic signals shape root architecture, growth restraint, senescence, source-sink balance, and reproductive protection. Wheat-specific evidence strongly supports the importance of HKT1;5-mediated Na⁺ retrieval, SOS-like ion regulation, K⁺ retention, antioxidant capacity, ABA-associated water regulation, osmotic adjustment, and genotype-dependent transcriptional responses. However, several important signaling models, including precise Ca2⁺ signatures, real-time Ca2⁺-ROS feedback dynamics, guard-cell ABA-ROS-Ca2⁺ signaling, systemic Ca2⁺/ROS waves, and salinity-specific sugar-redox-hormone control of grain filling, remain incompletely validated in wheat. By distinguishing wheat-supported mechanisms from conserved model-plant frameworks, this review identifies key signaling hubs and physiological trade-offs that may guide breeding, genome editing, priming, and agronomic strategies for improving wheat performance under saline environments.

Adaptive roles of plant secondary metabolites under drought stress conditions

Drought stress is among the most severe environmental constraints limiting plant growth, productivity and ecosystem stability worldwide. It disrupts cellular homeostasis, impairs photosynthesis, induces oxidative damage and alters metabolite profiles. In response, plants activate coordinated physiological and metabolic responses that reprogram carbon and nitrogen allocation toward protective functions. A major component of this adaptive response is the enhanced production of plant secondary metabolites, which contribute to stress tolerance through integrated biochemical, physiological and ecological mechanisms. This review synthesizes the major classes of drought-responsive secondary metabolites including phenylpropanoids, flavonoids, terpenoids, alkaloids and glucosinolates, and evaluates their biosynthetic pathways, regulatory networks and functional roles in drought adaptation. These metabolites contribute to antioxidant defense, membrane stabilization, osmotic adjustment, lignification and hormonal signaling, maintaining cellular homeostasis under drought stress. Their biosynthesis is coordinated through carbon and nitrogen reallocation via the shikimate, mevalonate, and methylerythritol phosphate pathways, and regulated by transcription factors, abscisic acid signaling and epigenetic modifications. Unlike previous reviews that discuss metabolite classes independently, this review integrates carbon–nitrogen allocation, metabolic trade-offs, regulatory networks and ecological interactions into a systems-level framework for understanding drought adaptation. Therefore, integrating molecular insights with breeding and metabolic engineering approaches facilitates the development of climate-resilient crops adapted to increasingly water-limited environments, supporting global food security and climate adaptation efforts.

Physiological, Biochemical, and Molecular Basis of Plant Responses to Drought Stress

The survival of plants in arid environments relies on their intricate responses to drought stress, encompassing physiological, biochemical, and molecular mechanisms. In the face of limited water availability, plants exhibit remarkable adaptations to minimize water loss and sustain vital functions. Physiologically, stomatal closure reduces transpirational water loss, while growth reduction and wilting help conserve water. Root growth alterations enable exploration of deeper soil layers for water acquisition. Biochemically, osmotic adjustment through accumulation of compatible solutes maintains cellular turgor pressure. Antioxidant production counteracts reactive oxygen species (ROS) induced by water stress. Notably, abscisic acid (ABA) accumulates, orchestrating stress responses including stomatal closure and gene regulation. Molecularly, gene expression changes underlie the activation of stress-responsive genes. Transcription factors like DREB and bZIP modulate gene expression, while ABA-dependent and ABA-independent pathways govern signaling. LEA proteins and chaperones shield cellular structures, and microRNAs fine-tune post-transcriptional regulation. This comprehensive framework underscores the remarkable capacity of plants to adapt to drought stress through an integrated network of physiological, biochemical, and molecular strategies. Understanding these responses holds promise for enhancing crop resilience and agricultural sustainability in water-scarce environments.

Brassinosteroids in plant growth and stress adaptation: molecular mechanisms and physiological functions