Temperature is vital in plant growth and agricultural fruit production. Litchi chinensis Sonn, commonly known as litchi, is appreciated for its delicious fruit and fragrant blossoms and is susceptible to stress when exposed to low temperatures. This study investigates the effect of two cryoprotectants that counteract cold stress during litchi flowering, identifies the genes that generate the cold resistance induced by the treatments, and hypothesizes the roles of these genes in cold resistance. Whole plants were treated with Bihu and Liangli cryoprotectant solutions to protect inflorescences below 10 °C. The soluble protein, sugar, fructose, sucrose, glucose, and proline contents were measured during inflorescence. Sucrose synthetase, sucrose phosphate synthetase, antioxidant enzymes (SOD, POD, CAT), and MDA were also monitored throughout the flowering stage. Differentially expressed genes (DEGs), gene ontology, and associated KEGG pathways in the transcriptomics study were investigated. There were 1243 DEGs expressed after Bihu treatment and 1340 in the control samples. Signal transduction pathways were associated with 39 genes in the control group and 43 genes in the Bihu treatment group. The discovery of these genes may contribute to further research on cold resistance mechanisms in litchi. The Bihu treatment was related to 422 low-temperature-sensitive differentially accumulated metabolites (DAMs), as opposed to 408 DAMs in the control, mostly associated with lipid metabolism, organic oxidants, and alcohols. Among them, the most significant differentially accumulated metabolites were involved in pathways such as β-alanine metabolism, polycyclic aromatic hydrocarbon biosynthesis, linoleic acid metabolism, and histidine metabolism. These results showed that Bihu treatment could potentially promote these favorable traits and increase fruit productivity compared to the Liangli and control treatments. More genomic research into cold stress is needed to support the findings of this study.

Objectives: Antibiotic-resistant bacterial infections are a growing global concern. A natural remedy for bacterial infections could be available in the Selenicereus undatus fruit, but its antibacterial and biochemical properties are not fully known. Methods: In this study, the biochemical composition and antibacterial, antioxidant, and cytotoxic activities of the Jindu No. 1 (JD) and Bird’s Nest (YW) dragon fruit varieties and their potential effects against E. coli, Pseudomonas sp., and Staphylococcus sp. were scrutinized. Results: The JD fruit extract showed higher antibacterial activity than the YW variety against E. coli, Pseudomonas sp., and Staphylococcus sp. in vitro. Additionally, the JD variety demonstrated more significant antioxidant activity than the YW variety and showed less cytotoxic activity. The JD variety had a higher glucose content, while the YW variety had a higher fructose content, and the phytoconstituents analysis confirmed 659 metabolites in total from the two varieties. Through in silico analyses, phytoconstituents were evaluated to identify potential drug molecules against the selected bacterial strain. Moreover, the molecular docking study revealed that riboprobe and Z-Gly-Pro might be effective against E. coli, 4-hydroxy retinoic acid, and that succinyl adenosine may target Pseudomonas sp., and xanthosine and 2′-deoxyinosine-5′-monophosphate may be effective against Staphylococcus sp. These results were further validated by 100 ns Molecular Dynamics (MD) simulation, and all of the selected compounds exhibited acceptable ADMET features. Conclusions: Therefore, phytoconstituents from S. undatus fruit varieties could be employed to fight human bacterial diseases, and future studies will support the continuation of other biological activities in medical research.

Background: The dramatic temperature fluctuations spurred by global warming and the accompanying extreme weather events inhibit mango growth and threaten mango productivity. Particularly, mango flowering is highly sensitive to temperature changes. The mango fruit setting rate was significantly positively correlated with pollen activity, and pollen activity was regulated by different metabolites. Methods: In this study, the in vitro pollen of two mango varieties (‘Renong No.1’ and ‘Jinhuang’), in which sensitivity to temperature differed significantly, were subjected to different temperature stresses (15 °C, 25 °C and 35 °C), and their metabolomics were analyzed. Results: The present results showed that 775 differential metabolites were screened by liquid chromatography–mass spectrometry and divided into 12 categories. The two varieties had significant differences in metabolite expression under different temperature stresses and the effect of low temperature on ‘Renong No.1’ mainly focused on amino acid metabolism, while the effect on ‘Jinhuang’ was mainly related to glycolysis. However, under the 35 °C temperature stress, ‘Renong No.1’ responded by redistributing riboflavin and betaine in vivo and the most obvious metabolic pathway of ‘Jinhuang’ enrichment was pyrimidine metabolism, which had undergone complex main body formation and extensive regulatory processes. The changes of metabolites of different varieties under low temperature and high temperature stress were different. Among them, flavonoids or flavonoid derivatives were included in class A (216 metabolites), C (163 metabolites) and D (233 metabolites) metabolites, indicating that flavonoid metabolites had an obvious regulatory effect on mango pollen metabolism under different temperature stress. Conclusions: The present results provide valuable information for reproductive biology studies and breeding in mango, in particular, the selection and breeding of the most suitable varieties for different production areas.

SHORT INTERNODE (SHI)-Related Sequence (SRS) transcription factors play crucial roles in plant growth, development, and stress responses and have been extensively studied in various plant species. However, the molecular functions and regulatory mechanisms of SRS genes in the economically important tropical fruit crop pitaya (Hylocereus undatus) remain poorly understood. This study identified 9 HuSRS genes in pitaya via bioinformatics analysis, with subcellular localization predicting nuclear distributions for all. Gene structure analysis showed 1–4 exons, and conserved motifs (RING-type zinc finger and IXGH domains) were shared across subclasses. Phylogenetic analysis classified the HuSRS genes into three subfamilies. Subfamily I (HuSRS1–HuSRS4) is closely related to poplar and tomato homologs and subfamily III (HuSRS6–HuSRS8) contains a recently duplicated paralogous pair (HuSRS7/HuSRS8) and shows affinity to rice SRS genes. Protein structure prediction revealed dominance of random coils, α-helices, and extended strands, with spatial similarity correlating to subfamily classification. Interaction networks showed HuSRS1, HuSRS2, HuSRS7 and HuSRS8 interact with functional proteins in transcription and hormone signaling. Promoter analysis identified abundant light/hormone/stress-responsive elements, with HuSRS5 harboring the most motifs. Transcriptome and qPCR analyses revealed spatiotemporal expression patterns: HuSRS4, HuSRS5, and HuSRS7 exhibited significantly higher expression levels in callus (WG), which may be associated with dedifferentiation capacity. In seedlings, HuSRS9 exhibited extremely high transcriptional accumulation in stem segments, while HuSRS1, HuSRS5, HuSRS7 and HuSRS8 were highly active in cotyledons. This study systematically analyzed the characteristics of the SRS gene family in pitaya, revealing its evolutionary conservation and spatio-temporal expression differences. The research results have laid a foundation for in-depth exploration of the function of the SRS gene in the tissue culture and molecular breeding of pitaya.

Introduction: Pitaya ( Hylocereus spp.), a rapidly expanding tropical fruit crop, faces a critical industry challenge: high yields often come at the expense of sweetness, limiting consumer appeal and market value. This study tests the hypothesis that cultivars with contrasting sugar phenotypes exhibit distinct profiles of sucrose-metabolizing enzyme activities, and that the balance between sucrose synthase (SS) cleavage and synthesis directions determines final sugar accumulation and spatial distribution patterns. Methods: We compared four phenotypically diverse cultivars selected based on preliminary field screening of three key traits: flesh color (white vs. pigmented), average fruit weight (small, medium, large), and soluble solids content (low, medium, high)—'Jindu No.1', 'White Crystal', 'Bicolor Fruit', and 'Bai Yulong'—through comprehensive assessments of morphological traits, soluble sugar profiles, and activities of key sucrose-metabolizing enzymes (neutral invertase [NI], acid invertase [AI], sucrose synthase [SS] in synthesis and cleavage directions, and sucrose phosphate synthase [SPS]) . Results: One-way ANOVA revealed significant genotypic variation in all measured traits, with sugar accumulation peaking in central fruit sectors and correlating strongly with enzyme activities. Notably, high SS-cleavage activity in 'Jindu No.1' and 'Bai Yulong' facilitated hexose buildup, while elevated SS-synthesis in 'Bicolor Fruit' diverted carbons away from sugars. Principal component analysis (PCA) integrated these traits, ranking quality as 'Bai Yulong' > 'Jindu No.1' > 'White Crystal' > 'Bicolor Fruit' and defining a "high-sugar" metabolic mode characterized by dominant SS cleavage. Discussion: These findings reveal physiological mechanisms driving quality differences and provide actionable biomarkers for molecular breeding of sweeter pitaya varieties, advancing sustainable industry development.