Gibberellic acid-stimulated Arabidopsis (GASA) gene family is a class of functional cysteine-rich proteins characterized by an N-terminal signal peptide and a C-terminal-conserved GASA domain with 12 invariant cysteine (Cys) residues. GASA proteins are widely distributed among plant species, and the majority of them are involved in the signal transmission of plant hormones, the regulation of plant development and growth, and the responses to different environmental constraints. To date, their action mechanisms are not completely elucidated. This review reports an overview of the diversity, structure, and subcellular localization of GASA proteins, their involvement in hormone crosstalk and redox regulation during development, and plant responses to abiotic and biotic stresses. Knowledge of this complex regulation can be a contribution to promoting multiple abiotic stress tolerance with potential agricultural applications through the engineering of genes encoding GASA proteins and the production of transgenic plants.

Salt-induced stress poses a significant barrier to agricultural productivity by impeding crop growth. Presently, environmentalists are dedicated to safeguarding food security by enhancing agricultural yields in challenging environments. Biostimulants play a crucial role in mitigating abiotic stresses in crop production, and among these, plant essential oils (EOs) stand out as organic substances with diverse biological effects on living organisms. Among the natural promoters of plant growth, Rosmarinus officinalis L. essential oil (RoEO) has gained considerable attention. Although the manifold effects of essential oils (EOs) on plant growth have been extensively demonstrated, their impact on salt stress tolerance in durum wheat seedlings remains unexplored. This investigation was undertaken to evaluate the biostimulatory capabilities of RoEO on the durum wheat cultivar “Mahmoudi.” The effects of three RoEO concentrations (1, 2.5, and 5 ppm) on seed germination, growth establishment, and the induction of salt resistance under salinity conditions (150 mM NaCl) were tested. At 5 ppm, RoEO enhanced seedlings’ tolerance to salinity by improving growth and reducing membrane deterioration and oxidative stress-induced damage. The expression profile analyses of seven stress-related genes (TdNHX1, TdSOS1, TdSOD, TdCAT, TdGA20-ox1, TdNRT2.1, and TdGS) using RT-qPCR showed enhancement of several important genes in durum wheat seedlings treated with 5 ppm RoEO, even under control conditions, which may be related to salt stress tolerance. The results indicate that the application of RoEO suggests a possible alternative strategy to increase salt tolerance in durum wheat seedlings towards better growth quality, thus increasing ROS scavenging and activation of antioxidant defense.

Cold stress is a key environmental factor affecting plant growth and development, crop productivity, and geographic distribution. Thioredoxins (Trxs) are small proteins that are ubiquitously expressed in all organisms and implicated in several cellular processes, including redox reactions. However, their role in the regulation of cold stress in the halophyte plant Lobularia maritima remains unknown. We recently showed that overexpression of LmTrxh2, which is the gene that encodes the h-type Trx protein previously isolated from L. maritima, led to an enhanced tolerance to salt and osmotic stress in transgenic tobacco. This study functionally characterized the LmTrxh2 gene via its overexpression in tobacco and explored its cold tolerance mechanisms. Results of the RT-qPCR and western blot analyses indicated differential temporal and spatial regulation of LmTrxh2 in L. maritima under cold stress at 4 °C. LmTrxh2 overexpression enhanced the cold tolerance of transgenic tobacco, as evidenced by increased germination rate, fresh weight and catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) activities; reduced malondialdehyde levels, membrane leakage, superoxide anion (O₂⁻), and hydrogen peroxide (H₂O₂) levels; and higher retention of chlorophyll than in non-transgenic plants (NT). Furthermore, the transcript levels of reactive oxygen species (ROS)-related genes (NtSOD and NtCAT1), stress-responsive late embryogenis abundant protein 5 (NtLEA5), early response to dehydration 10C (NtERD10C), DRE-binding proteins 1A (NtDREB1A), and cold-responsive (COR) genes (NtCOR15A, NtCOR47, and NtKIN1) were upregulated in transgenic lines compared with those in NT plants under cold stress, indicating that LmTrxh2 conferred cold stress tolerance by enhancing the ROS scavenging ability of plants, thus enabling them to maintain membrane integrity. These results suggest that LmTrxh2 promotes cold tolerance in tobacco and provide new insight into the improvement of cold-stress resistance to cold stress in non-halophyte plants and crops.

Plant defensins (PDFs) are a group of cationic antimicrobial peptides that are distinguished by their unique tertiary structure and play significant roles in physiological metabolism, growth, and stress tolerance. Defensins are key components of plant innate immunity; they can target a wide variety of microorganisms. This study aimed to identify and investigate the role of Triticum durum PDFs (TdPDFs) in response to environmental stresses. Prior to this, in silico analyses of TdPDF genes were conducted to assess their chromosomal locations, conserved motifs, exon–intron distribution, and cis-regulatory elements in the promoter regions. Additionally, bioinformatic analyses were performed to characterize the structure of TdPDF proteins, evaluate their phylogenetic relationships, predict their subcellular localization, and estimate their physicochemical properties. Docking studies were conducted to assess the interactions between TdPDF proteins and the fungal plasma membrane. A total of 28 TdPDF genes were identified in durum wheat based on their conserved domain PF00304 (gamma-thionin). These genes are distributed across all chromosomes of the durum wheat genome, except for chromosomes 4A and 7A. Analysis of the promoters of these genes revealed numerous elements associated with development, hormone responsiveness, and environmental stress. The majority of TdPDF proteins were predicted to be located extracellular. In addition, TdPDF proteins were classified into three clusters based on sequence similarity. Phylogenetic analysis suggested that TdPDF proteins share ancestral similarities with the PDF sequences of other monocotyledonous species. Molecular docking studies revealed that TdPDF proteins interact with fungal plasma membranes, suggesting that they play a critical role in the resistance of plants to pathogen infections. Expression analysis underlined the crucial role of nine TdPDF genes in the defense responses of durum wheat against both pathogenic and environmental stressors. Overall, our findings underscore the potential of TdPDF genes in host-plant resistance and highlight opportunities for their application in crop improvement toward stress tolerance.