Drought, the most significant environmental stressor, severely limits plant growth and development and significantly reduces crop production. Drought stress responses vary among plants, allowing them to withstand and survive adverse conditions. Plants resist drought by maintaining signaling pathways, such as the abscisic acid pathway, and activating unusual proteins, such as dehydrins. This study aims to investigate signaling pathways and the biological structures and activities of proteins involved in these processes. We also look into the occurrence of crosstalk across multiple signaling pathways and what it means for agricultural plant enhancement. By incorporating the most common components across all abiotic stress situations, this review provides insight into the evolution of drought stress tolerance in agricultural plants. This review could be helpful for crop drought stress researchers.

Long-chain acyl-CoA synthetases (LACSs) catalyze fatty acids (FAs) to form fatty acyl-CoA thioesters, which play essential roles in FA and lipid metabolisms and cuticle wax biosynthesis. Although LACSs from Arabidopsis have been intensively studied, the characterization and function of LACSs from poplar are unexplored. Here, 10 poplar PtLACS genes were identified from the poplar genome and distributed to eight chromosomes. A phylogenetic tree indicated that PtLACSs are sorted into six clades. Collinearity analysis and duplication events demonstrated that PtLACSs expand through segmental replication events and experience purifying selective pressure during the evolutionary process. Expression patterns revealed that PtLACSs have divergent expression changes in response to abiotic stress. Interaction proteins and GO analysis could enhance the understanding of putative interactions among protein and gene regulatory networks related to FA and lipid metabolisms. Cluster networks and long-chain FA (LCFA) and very long-chain FA (VLCFA) content analysis revealed the possible regulatory mechanism in response to drought and salt stresses in poplar. The present study provides valuable information for the functional identification of PtLACSs in response to abiotic stress metabolism in poplar.

An immune system is a protective mechanism that shields plants from environmental stresses. This primary function is to maintain optimal circumstances for the growth and development of plant tissues while avoiding harm from biotic and abiotic stress factors. Plants subjected to various stressors initiate stress signaling cascades that affect multiple gene expressions and induce adaptation. These signaling pathways are coordinated by transcription factors, non-coding RNAs, RNA-binding proteins, and protein–protein interaction networks. Several studies have focused on various immune systems, but no study has collected all of them together to illustrate them efficiently. According to this review, stress-responsive genes encode ion and water transporters, enzymes, and transcription factors, making plants more resistant to biological and abiotic challenges. Plants have also evolved anti-pathogen defense systems such as regulatory hormone pathways, reactive oxygen species generation, gene expression, programmed cell death, and cell survival. Plants produce short RNAs in response to a viral attack, which silences the offensive genome and creates complex epigenetic regulatory mechanisms such as histone changes, chromatin remodeling, and DNA methylation to protect plants from pathogens. This review provides an in-depth description of proteins, effectors, and pathways included in plant resistance against environmental stresses and offers details on future trends, such as metabolic pathways and genetic engineering, to improve the protection of plants against stress-induced responses.

Fatty acid desaturases (FADs) modulate carbon–carbon single bonds to form carbon–carbon double bonds in acyl chains, leading to unsaturated fatty acids (UFAs) that have vital roles in plant growth and development and their response to environmental stresses. In this study, a total of 23 Populus trichocarpaFAD (PtFAD) candidates were identified from the poplar genome and clustered into seven clades, including FAB2, FAD2, FAD3/7/8, FAD5, FAD6, DSD, and SLD. The exon–intron compositions and conserved motifs of the PtFADs, clustered into the same clade, were considerably conserved. It was found that segmental duplication events are predominantly attributable to the PtFAD gene family expansion. Several hormone- and stress-responsive elements in the PtFAD promoters implied that the expression of the PtFAD members was complicatedly regulated. A gene expression pattern analysis revealed that some PtFAD mRNA levels were significantly induced by abiotic stress. An interaction proteins and gene ontology (GO) analysis indicated that the PtFADs are closely associated with the UFAs biosynthesis. In addition, the UFA contents in poplars were significantly changed under drought and salt stresses, especially the ratio of linoleic and linolenic acids. The integration of the PtFAD expression patterns and UFA contents showed that the abiotic stress-induced PtFAD3/7/8 members mediating the conversion of linoleic and linolenic acids play vital roles in response to osmotic stress. This study highlights the profiles and functions of the PtFADs and identifies some valuable genes for forest improvements.