Poa pratensis is one of the world’s most widely planted cold-season turfgrasses, with good quality but poor drought resistance. When plants suffer from stress, the metabolism of soluble sugar takes place, which is a dynamic process involving both degradation and synthesis. A detailed and in-depth study of the sugar metabolism process in plants’ response to stress will help us to understand the internal mechanism of plant adaptation to stress. In this study, the ‘10-202’ ecotype with drought resistance and the ‘Blue moon’ ecotype with drought sensitivity were used to explore the sugar metabolism process in response to drought stress. The results showed that drought stress induced sucrose accumulation in the leaves and roots, promoted increases in SPS, S-AI, and PpN/A-Inv activities, as well as gene expression in the leaves, and changed the content and distribution of fructose, glucose, sucrose, maltose, and trehalose in vivo. Compared with ‘Blue moon’, ‘10-202’ had higher trehalose content in leaves under normal conditions, and its roots could accumulate more fructose and glucose to maintain the balance of osmotic potential and redox under drought stress. Meanwhile, PpSWEET1b, -12, and -15 in the leaves and roots of the two ecotypes were significantly induced by drought stress. The improvements in sucrose accumulation and decomposition efficiency in leaves under drought stress is conducive to enhancing drought resistance in plants. PpSWEET1b plays a vital role in regulating the sugar transport process of drought tolerance in turfgrass.

The tall wheatgrass Thinopyrum ponticum has excellent saline–alkali tolerance and great potential for restoring saline–alkali land to enhance productivity. This study used the Thinopyrum ponticum cv. “Orbit” variety, which is widely planted in saline–alkali pastures, as the material and artificially simulated salt stress using 150 mM NaCl and 150 mM Na₂SO₄, respectively. The growth and physiological indexes of the leaves and roots of seedlings were measured after various treatment durations, and the transcriptomes of untreated and Na₂SO₄-treated leaves and roots were also analyzed after 24 h of treatment. The results showed that salt stress resulted in significant reductions in leaf relative water content in seedlings and inhibited root elongation growth, with Na₂SO₄ treatment producing a greater impact on plant growth than NaCl treatment. Salt stress significantly alters ion transport and distribution in Thinopyrum ponticum, characterized by pronounced Na⁺ accumulation and a concomitant decline in K⁺ uptake. Additionally, to adapt to salt stress, roots enhance their ability to absorb and transport essential cations, such as Ca²⁺, Mg²⁺, Fe³⁺, and Cu²⁺. RNA-Seq analysis identified 1682 and 2816 differentially expressed genes (DEGs) in leaves and roots under Na₂SO₄ stress, respectively, with 210 common DEGs. Enrichment analyses revealed that DEGs were primarily associated with redox homeostasis, ion balance, and signal transduction. Furthermore, transcription regulation analysis indicated the Thinopyrum ponticum can coordinate the activation of NAC/MYB/WRKY transcription factors, SA/ETH hormone signaling, and Ca²⁺ pathways in response to salt stress. In summary, this study systematically reveals for the first time the molecular mechanisms by which Thinopyrum ponticum responds to Na₂SO₄ stress through coordinated regulation of ion transport, transcription factor networks, and hormone-Ca²⁺ signaling pathways. Based on transcriptomic and protein–protein interaction analyses, nine key candidate genes for saline–alkali tolerance were identified, including UGT7472, JMT, T4E14.7, CAX5, CP1, PXG2 NAMT1, BON3, and APX7. These findings provide novel genetic resources and a theoretical foundation for breeding salt–alkali-tolerant crops.

Background: The Domain of unknown function 679 membrane proteins (DMPs) family, as a green plant-specific membrane protein, plays an important role in plant reproductive development, stress response and aging. To identify the DMP gene members of oat (AsDMP) and to investigate their family structural features and tissue expression profile characteristics, a study was conducted. Based on the whole genome and transcriptome data, in this investigation, we have scrutinized the physicochemical properties, gene structure, cisacting elements, phylogenetic relationships, conserved structural (CS) domains, CS motifs and expression patterns of the AsDMP family of oat. Results The DMP family genes of oat were found distributed across 17 chromosomal scaffolds with 33 members. We could divide the AsDMP genes into five subfamilies based on phylogenetic relationships. The gene structure suggests that oats may have also undergone an intron loss event during evolution. Covariance analysis suggests that genome-wide duplication/segmental duplication may be the major contributor to the expansion of the AsDMP gene family. Ka/Ks selective pressure analysis of oat DMP gene family, suggests that DMP gene pairs tend to be conserved over evolutionary time. The upstream promoter of these genes containing several cis-acting elements indicates a plausible role in abiotic stress and hormone induction. Gene expression pattern according to transcriptome data revealed participation of the DMP genes in tissue and organ development. In this study, AsDMP genes (AsDMP1, AsDMP19, and AsDMP22) were identified as potentially regulating oat seed senescence, and can be used as candidate genes for seed longevity and anti-aging germplasm breeding studies in oat. The study provides valuable information on the regulatory mechanism of the AsDMP gene family in the aging process of oat germplasm, and also provides theoretical support for further function investigation in the oat DMP gene and the molecular mechanism of seed anti-aging. Conclusions In this study, we found that the AsDMP gene is involved in the aging process of oat seeds, which is the first report on the potential role of DMP genes in oat seeds.

Thinopyrum ponticum, a salt-tolerant grass widely used in the restoration of saline–alkali lands, was the focus of this study. Two accessions with contrasting salt tolerance—‘4–6’ (salt tolerant) and ‘5–22’ (salt sensitive)—were watered with 500 mM NaCl solution for 14 days, and seedling growth and physiological responses were assessed. Salt stress significantly inhibited the growth of both accessions, but ‘4–6’ was less impacted. Morphologically, ‘4–6’ adapted to stress by increasing the root-to-shoot ratio, increasing leaf length, and decreasing leaf width. In contrast, the growth of ‘5–22’ was comprehensively inhibited, with significant reductions in fresh weight, dry weight, leaf length, and leaf area. Physiologically, the contents of malondialdehyde and proline increased in both accessions, but ‘4–6’ exhibited stronger antioxidant capacity and more flexible regulation of sugar metabolism (with sucrose decreasing while fructose and glucose increased) to maintain osmotic balance. In comparison, ‘5–22’ showed dysregulated sugar metabolism, characterized by sucrose accumulation and a decrease in fructose, which exacerbated salt damage. Regarding hormones under salt stress, IAA content increased in leaves of ‘4–6’ but decreased in ‘5–22’. Jasmonate-related hormones decreased in both accessions; however, ‘4–6’ maintained higher basal levels and smaller reductions, indicating stronger hormonal regulation capacity. Correlation analysis confirmed that IAA- and JA-related hormones play important roles in salt tolerance of Thinopyrum ponticum. In terms of ion balance, ‘4–6’ maintained higher K⁺/Na⁺ and Ca²⁺/Na⁺ ratios, promoted beneficial cation transport to shoots, and restricted Cl⁻ accumulation. In contrast, ‘5–22’ suffered from disrupted ion balance and excessive Cl⁻ accumulation, resulting in severe growth inhibition. In addition, the key indicators screened by RDA provide an important reference for revealing the salt tolerance mechanism of Thinopyrum ponticum and for constructing a corresponding evaluation system. This study elucidates the mechanisms underlying differential salt tolerance among Thinopyrum ponticum accessions, highlighting the coordinated role of hormonal reprogramming and ion homeostasis. These findings offer both theoretical insights and practical guidance for breeding new salt-tolerant varieties of Thinopyrum ponticum and for the amelioration of saline–alkali lands.