Oil palm (Elaeis guineensis), a tropical crop, is highly sensitive to temperature fluctuations, with low temperatures significantly limiting its growth, development, and geographical distribution. Understanding the adaptive mechanisms of oil palm under low-temperature stress is essential for developing cold-tolerant varieties. This study focused on analyzing the physiological and metabolomic responses of annual thin-shell oil palm seedlings to low-temperature exposure (8 °C) for different time periods: 0 h (CK), 0.5 h (CD05), 1 h (CD1), 2 h (CD2), 4 h (CD4), and 8 h (CD8). Physiological analysis showed a significant increase in the activity of antioxidant enzymes, such as superoxide dismutase (SOD) and peroxidase (POD), highlighting the activation of oxidative stress defense mechanisms. Concurrently, elevated relative conductivity, indicated cell membrane damage, a common consequence of cold-induced oxidative stress. Metabolomic profiling using LC-MS/MS revealed significant changes in metabolite composition, with differential metabolites predominately enriched in key metabolic pathways such as arginine and proline metabolism, glycine, serine, and threonine metabolism, plant hormone biosynthesis, and flavonoid biosynthesis pathways. Notable metabolites such as citric acid, L-aspartic acid, L-tryptophan, and vitexin showed significant accumulation, indicating their roles in enhancing cold tolerance through improved antioxidant defenses, promoting osmoregulation, and stabilizing cellular structures. Correlation analysis further emphasized the importance of flavonoids and plant hormones in the cold stress response. In particular, vitexin, isovitexin, and apigenin 6-C-glucoside were significantly enriched, suggesting their contribution to antioxidant and stress signaling networks. Furthermore, metabolites involved in amino acid metabolism, including L-glutamic acid, sarcosine, and proline, were upregulated, supporting enhanced protein synthesis and cellular repair under stress. This metabolic reprogramming correlated with physiological improvements, as evidenced by increased relative conductivity and post cold exposure growth recovery. This study provides critical insights into the physiological and metabolic adaptations of oil palm to cold stress, emphasizing the significant role of secondary metabolites—such as flavonoids, amino acids, and plant hormones—in enhancing cold tolerance. Theses metabolites contribute to oxidative stress protection, osmotic regulation, and cell wall stabilization enabling the plant to better withstand with low temperature condition. The findings provide a strong foundation for molecular research and breeding initiatives aimed at developing cold tolerant oil palm varieties, a crop of siginificant economic value. By combining metabolomic profiling with physiological analyses, provides a holistic understanding of the adaptive mechanisms in oil palm under cold stress.This integrated approach identifies key metabolic pathways that can be targeted in breeding programs to enhance cold resilience, paving the way for improved crop performance in challenging environments.

Coconut meat and coconut water have garnered significant attention for their richness in healthful flavonoids. However, the dynamics of flavonoid metabolites in coconut water during different developmental stages remain poorly understood. This study employed the metabolomics approach using liquid chromatography-tandem mass spectrometry (LC-MS/MS) to investigate the changes in flavonoid metabolite profiles in coconut water from two varieties, ‘Wenye No.5’(W5) and Hainan local coconut (CK), across six developmental stages. The results showed that a total of 123 flavonoid metabolites including chalcones, dihydroflavonoids, dihydroflavonols, flavonoids, flavonols, flavonoid carboglycosides, and flavanols were identified in the coconut water as compared to the control. The total flavonoid content in both types of coconut water exhibited a decreasing trend with developmental progression, but the total flavonoid content in CK was significantly higher than that in W5. The number of flavonoid metabolites that differed significantly between the W5 and CK groups at different developmental stages were 74, 74, 60, 92, 40 and 54, respectively. KEGG pathway analysis revealed 38 differential metabolites involved in key pathways for flavonoid biosynthesis and secondary metabolite biosynthesis. This study provides new insights into the dynamics of flavonoid metabolites in coconut water and highlights the potential for selecting and breeding high-quality coconuts with enhanced flavonoid content. The findings have implications for the development of coconut-based products with improved nutritional and functional properties.

Plants from invasive populations often have higher growth rates than conspecifics from native populations due to better environmental adaptability. However, the roles of improved chlorophyll fluorescence or antioxidant defenses in helping them to grow better under adverse situations are insufficient, even though this is a key physiological question for elucidating mechanisms of plant invasion. Here, we conducted experiments with eight native (China) and eight introduced (USA) populations of Chinese tallow tree (Triadica sebifera). We tested how salinity, nutrients (overall amount or N:P in two separate experiments) and their interaction affected T. sebifera aboveground biomass, leaf area, chlorophyll fluorescence and antioxidant defenses. Plants from introduced populations were larger than those from native populations, but salinity and nutrient shortage (low nutrients or high N:P) reduced this advantage, possibly reflecting differences in chlorophyll fluorescence based on their higher PSII maximum photochemical efficiency (F_v/F_m) and PSI maximum photo-oxidizable P700 in higher nutrient conditions. Native population plants had lower F_v/F_m with saline. Except in high nutrients/N:P with salinity, introduced population plants had lower electron transfer rate and photochemical quantum yield. There were no differences in antioxidant defenses between introduced and native populations except accumulation of hydrogen peroxide (H₂O₂), which was lower for introduced populations. Low nutrients and higher N:P or salinity increased total antioxidant capacity and H₂O₂. Our results indicate that nutrients and salinity induce differences in H₂O₂ contents and chlorophyll fluorescence characteristics between introduced and native populations of an invasive plant, illuminating adaptive mechanisms using photosynthetic physiological descriptors in order to predict invasions.

Salt stress is widely recognized as a major abiotic constraint that limits plant growth and productivity. Alfalfa (Medicago sativa L.), a globally important forage legume, exhibits considerable variability in salt toll,erance across its diverse cultivars. The present study aims to provide a comprehensive evaluation of eight alfalfa varieties by examining their morphological, physiological, and biochemical responses at four NaCl levels (0, 60, 120, and 180 mM NaCl). Salt tolerance is quantified using a combination of the membership function method, correlation analysis, principal component analysis, and different indices of salt tolerance. High salt stress significantly reduced plant height (PH), shoot dry weight (SDW), root dry weight (RDW), and number of leaves (NOL) of all alfalfa varieties by 47.21%, 61.36%, 64.19%, and 59.91%, respectively, compared with the control. Similarly, physiological traits including relative water content (RWC) and stomatal conductance (SC) declined by 43.93% and 60.87%, respectively, whereas electrolyte leakage (EL) and malondialdehyde (MDA) increased by 267.35% and 178.48%, respectively. Salt stress also markedly altered antioxidant responses among varieties, with superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities increasing by 111.27%, 170.87%, and 125.87%, while V5 (A'erjienong) and V2 (Weinasi) consistently showed tolerance, whereas V4 (Fudina) and V8 (Qianjing) exhibited susceptibility across varying stress levels. Principal component analysis (PCA) classified the traits into three main groups, which explained 93.15% of the total variation, and identified SOD, POD, CAT, SS, and Car as crucial factors affecting salt tolerance. Comprehensive membership function analysis indicated that variety V5 (A'erjienong) was the most tolerant, while variety V4 (Fudina) remained the most sensitive. This study highlights the importance of morpho-physiological and biochemical traits, along with stress tolerance indices, as reliable indicators for evaluating salt tolerance in alfalfa. Future integration of these traits with advanced genetic and breeding approaches may facilitate the development of high-yielding, salt-tolerant alfalfa cultivars.

Oil palm (Elaeis guineensis Jacq.) is a quintessential tropical oilseed crop, whose distribution and yield are significantly constrained by low-temperature stress. This study conducted physiological and proteomic analyses to investigate the early response mechanisms of one-year-old thin-shelled oil palm seedlings exposed to low temperatures of 8 °C for durations of 0, 0.5, 1, 2, 4, and 8 h. The results indicated that low-temperature treatment inhibited chlorophyll accumulation, reduced photosynthetic efficiency, and increased the levels of malondialdehyde (MDA) and soluble sugars. Concurrently, the activities of antioxidant enzymes exhibited a transient increase, suggesting an imbalance in the antioxidant defense system during the later stages of stress. Proteomics results indicate that the core pathways involved are fatty acid degradation and the regulatory pathways for starch and sucrose metabolism. Within these pathways, key proteins such as ACSL (long-chain fatty acid-CoA ligase), paaF (enoyl-CoA hydratase), HADH (3-hydroxyacyl-CoA dehydrogenase), and HADHA (enoyl-CoA hydratase/long-chain 3-hydroxyacyl-CoA dehydrogenase) are identified among 13 differential accumulation protein (DAPs). It is hypothesized that these key proteins work in concert to regulate osmosis, scavenge reactive oxygen species (ROS), stabilize membranes, and supply energy. Through physiological and proteomic analyses, this study identified physiological indicators, key proteins, and regulatory pathways associated with cold tolerance in oil palm, thus providing a theoretical basis for breeding low-temperature-tolerant oil palm varieties. The findings contribute to the development of low-temperature-tolerant oil palm cultivars.