Search Results (258)

Citrullus colocynthis (L.) Schrad. (Cucurbitaceae) is a medicinal plant, renowned since antiquity, widely used in traditional medicine for the management of metabolic and inflammatory disorders: seed extracts particularly are reported for the management of rheumatoid arthritis, articular inflammation and skin wound recovery. Our aim was to comparatively evaluate the antioxidant and anti-inflammatory activities of aqueous and oily extracts obtained from mature and immature seeds, and to preliminarily assess their dermal tolerance and protective effects against induced inflammation and UV damage. Antioxidant activity was investigated in vitro using β-carotene bleaching and ferric reducing antioxidant power (FRAP) assays, whereas anti-inflammatory activity and anti-irritation effects were evaluated in vivo in a mouse model using the xylene-induced ear edema and the UV-induced skin irritation test. Oily extracts from both maturation stages showed marked inhibition of β-carotene oxidation, while the aqueous extract of immature seeds exhibited the highest ferric reducing capacity; on the other hand, fixed oils demonstrated a significantly greater inhibitory effect on oedema, suggesting a higher efficacy in modulating acute inflammatory responses. Results showed how C. colocynthis seed maturity and extraction solvent influence the bioactive potential of these ingredients for phytotherapeutic and dermo-functional applications, supporting a possible use against wrinkle formation and UV-induced skin alterations. Full article

Citrullus colocynthis (L.) Schrad., a drought-tolerant member of the Cucurbitaceae family, has been used in traditional medicine for centuries and has recently attracted increasing interest because of its potential pharmacological, agricultural, and ecological applications. This review examines current information on the plant’s distribution, ethnomedicinal uses, phytochemical composition, biological activities, applications in poultry, and ecological significance. Its bioactive constituents include cucurbitacins, flavonoids, phenolic compounds, alkaloids, glycosides, fatty acids, and tocopherols. These compounds have been associated with anticancer, antidiabetic, antimicrobial, antioxidant, anti-inflammatory, neuroprotective, hepatoprotective, and other biological activities, although most of the available evidence comes from in-vitro and preclinical studies. Initial findings also indicate that the plant may have value as a phytogenic feed additive in poultry and as a drought-tolerant species for soil stabilization, rangeland rehabilitation, and desertification control. However, the practical application of these findings is still constrained by differences in research methods, variation in phytochemical composition, limited clinical evidence, and the plant’s narrow therapeutic window and dose-dependent toxicity. Consequently, its therapeutic effectiveness and suitability for routine agricultural use cannot yet be established with certainty. Future research should focus on phytochemical standardization, quality control, thorough toxicological assessment, mechanistic studies, and well-designed clinical and animal trials using standardized preparations. Collectively, the available evidence indicates that C. colocynthis is a promising source of bioactive compounds with potential pharmaceutical, veterinary, and ecological applications, although rigorous scientific validation is required before its safe and effective utilization can be recommended. Full article

Grafting is an important technique in watermelon production systems to enhance biotic and abiotic stress tolerance, fruit yield, and quality. Grafting watermelon using compatible rootstocks of closely related Citrullus species offers opportunities for the development of watermelon crops possessing unique product profiles. Therefore, the objective of this review is to appraise the utilities of citron watermelon as a potential and candidate rootstock for grafted watermelon to develop unique graft combinations possessing market and consumer-needed attributes. We conducted a search in various databases, including Web of Science, Science Direct, and Scopus, and accessed the relevant peer-reviewed publications and composed five sections for the review. The first section outlined the benefits of citron watermelon rootstock on grafted watermelon against biotic stress tolerance. The second section discussed the impact of citron watermelon rootstock for inducing abiotic stress tolerance in grafted watermelon. Thirdly, citron watermelon rootstock/watermelon scion on fruit yield is discussed. The fourth section reviews fruit quality of grafted sweet watermelon as affected by citron watermelon rootstocks. Lastly, the genetic resources of citron watermelon and their attributes for rootstock applications in grafted watermelon are presented. The findings highlight citron watermelon as a promising alternative rootstock for improving resilience and fruit quality in grafted sweet watermelon production systems. Full article

Auxin response factors (ARFs) are key transcription factors regulating plant growth and development, but their functions and molecular mechanisms in stem elongation of cucurbit crops remain unclear. In this study, we identified a nuclear-localized ARF member, ClARF4, in watermelon. ClARF4 knockout lines were generated using CRISPR-Cas9 technology and exhibited significant reductions in plant height, internode number, and internode length. Cytological analysis indicated that the dwarf phenotype resulted from inhibited longitudinal cell elongation in stems. Transcriptome analysis revealed that ClARF4 modulates cell size by regulating the expression of genes involved in auxin signaling and response pathways. Furthermore, using yeast two-hybrid screening, we identified ClPetC, a component of the photosynthetic electron transport chain, as an interacting protein of ClARF4; bimolecular fluorescence complementation (BiFC) assays further confirmed their direct interaction in the plant nucleus. This study not only reveals the key role of ClARF4 in regulating plant height in watermelon, but also provides important insights into the function of chloroplast–nucleus signaling crosstalk in plant architecture establishment by identifying the interaction between ClARF4 and the chloroplast protein ClPetC in the nucleus. Full article

Water scarcity caused by irregular rainfall and high evapotranspiration rates in the Brazilian semi-arid region is one of the main factors limiting watermelon cultivation, underscoring the need for irrigation strategies capable of mitigating the adverse effects of water deficit. This study aimed to evaluate the effects of foliar salicylic acid application on the induction of water-deficit tolerance in watermelon plants subjected to water restriction at different phenological stages under semi-arid conditions. The experiment was conducted using a randomized block design in a split-plot arrangement, with five irrigation management strategies based on crop evapotranspiration (ETc) and four salicylic acid (SA) concentrations, with three replications and three plants per plot. Water deficit adversely affected the morphophysiological traits of the plants and the physical and chemical attributes of ‘Crimson Sweet’ watermelon fruits, with water restriction during the vegetative and flowering stages causing the most severe effects. Foliar application of salicylic acid at concentrations ranging from 1.2 to 2.6 mM increased relative water content by 9.4%, reduced electrolyte leakage by 11.60%, and enhanced CO₂ assimilation by 18.82%, instantaneous water-use efficiency in 128.10%, and instantaneous carboxylation efficiency by 46.92%. Salicylic acid concentrations within this range also improved plant water status, gas exchange, photosynthetic pigment content, growth, and the physical and chemical attributes of the fruits. In contrast, concentrations above 2.6 mM reduced gas exchange, photosynthetic pigment accumulation, chlorophyll a fluorescence, and the physical and chemical quality of ‘Crimson Sweet’ watermelon fruits. Thus, salicylic acid may be an alternative to modulate the tolerance of watermelon plants under water deficit during phenological phases. Full article

Auxin response factors (ARFs) are a pivotal class of transcription factors that mediate auxin signaling, playing critical roles in plant growth, development, and stress adaptation. Watermelon (Citrullus lanatus) is an economically important cucurbit crop, yet a comprehensive analysis of its ARF gene family under abiotic stresses is limited. In this study, we conducted a genome-wide identification of the ARF gene family in watermelon. A total of 16 ClARF genes were identified and unevenly distributed across nine chromosomes. Phylogenetic analysis classified these ClARF proteins into four distinct classes (I–IV), a categorization supported by conserved motif composition and exon-intron structures. Cis-element analysis revealed that ClARF gene promoters are enriched with motifs related to hormone response, light signaling, and various stresses, suggesting their involvement in diverse regulatory pathways. Syntenic analysis indicated that segmental duplication events have contributed to the expansion and evolution of the ClARF family. Tissue-specific expression profiling showed varied expression patterns across roots, stems, leaves, tendrils, and flowers, implying functional diversification. Furthermore, real-time quantitative PCR (RT-qPCR) analysis revealed stress-specific expression patterns of ClARF genes. Notably, ClARF6 was consistently upregulated across all three treatments and showed the highest induction under drought (~7-fold) and cold (~11-fold), while ClARF13 was most strongly induced under salt stress at 48 h (~10-fold), and ClARF1 was consistently downregulated across all treatments. This study provides a stress-oriented expression profiling of the ARF gene family in watermelon, establishing a foundation for future functional studies and offering candidate genes for further functional characterization of abiotic-stress responses in watermelon and related cucurbit crops. Full article

Root-knot nematodes (RKNs) are among the most destructive pests in protected watermelon production under continuous cropping systems. Although both pepper rotation and arbuscular mycorrhizal fungi (AMF) inoculation have shown potential for suppressing RKNs and promoting plant growth, their combined effects remain unclear. This study conducted greenhouse pot experiments using continuously cropped watermelon soil over two consecutive cycles. In the first cycle, chili pepper (Capsicum annuum) or watermelon (Citrullus lanatus) was planted, followed by watermelon cultivation in the second cycle with inoculation of Funneliformis mosseae or Glomus versiforme. Compared with continuous watermelon cropping, both rotation and AMF inoculation improved root vitality, osmotic regulation, antioxidant enzyme activities, and photosynthetic performance, thereby enhancing watermelon growth and resistance to RKNs. Among all treatments, chili pepper rotation combined with Glomus versiforme showed the best performance, increasing shoot fresh weight by 31% and reducing disease index (DI), gall index (GI), and egg mass index (EI) by 30.8%, 77.0%, and 57.1%, respectively. In addition, the populations of second-stage juveniles (J2) in soil and roots and adult females in roots decreased by 85.4%, 55.5%, and 50.8%, respectively. High-throughput sequencing results showed that the combined treatment enriched several potentially beneficial microbial taxa, including Ochrobactrum, Bacillus, Acinetobacter, and Delftia. In addition, it enriched predicted metabolic pathways that may be associated with plant growth promotion and stress tolerance. Overall, pepper rotation combined with Glomus versiforme inoculation represents a promising, environmentally friendly strategy for the management of watermelon root-knot nematode disease. Full article

Pollinator health depends critically on gut microbiome composition, yet species-specific responses to agricultural environments remain unclear. We compared gut microbiome dynamics and dietary shifts in Osmia excavata, Megachile rotundata, and Apis cerana during alfalfa pollination using 16S rRNA sequencing and rbcL metabarcoding. Alpha diversity revealed distinct patterns: O. excavata showed reduced richness but increased evenness after foraging, M. rotundata exhibited reduced diversity, while A. cerana remained stable. Beta diversity demonstrated microbiome convergence among species after release, indicating environmental filtering. Dietary analysis revealed polylectic foraging dominated by Citrullus lanatus, Peganum nigellastrum, and Zea mays, with minimal alfalfa consumption. Pseudomonadota and Bacillota predominated, with species-specific signatures: Gilliamella in A. cerana, Lactobacillus in M. rotundata, and Bacillus in O. excavata. These findings demonstrate that microbiome assembly reflects host sociality–environment interactions, with solitary bees showing greater plasticity. This study provides a microbial foundation for pollinator conservation in agricultural systems. Full article

Endophytic bacteria from plants adapted to arid and semi-arid environments represent an underexplored reservoir of microbial diversity with potential agricultural applications. Here, we report a polyphasic taxonomic and genome-based characterization of Achromobacter sp. isolates recovered from root and foliar tissues of Citrullus colocynthis and Peganum harmala, two medicinal plants thriving under harsh environmental conditions. Whole-genome sequencing, phylogenomic analyses, average nucleotide identity (ANI), digital DNA–DNA hybridization (dDDH), multilocus sequence typing, and detailed phenotypic profiling revealed three previously undescribed species, for which we propose the names Achromobacter colocynthi sp. nov., Achromobacter maghribensis sp. nov., and Achromobacter semiaridum sp. nov. Genome assemblies were highly complete (98.7–99.2%) with minimal contamination (<1%), supporting robust taxonomic inference. All three species displayed ANI and dDDH values below accepted thresholds relative to their closest phylogenetic neighbors, despite partial inconsistencies in 16S rRNA similarity for one isolate, highlighting the value of genome-wide metrics for species delineation. Phylogenomic analyses placed the novel taxa within Achromobacter sp. as distinct evolutionary lineages. Phenotypic characterization indicated broad metabolic versatility, including utilization of carbohydrates, organic acids, and amino acids, tolerance to moderate salinity and acidic pH, and resistance to multiple antimicrobial compounds, traits likely linked to adaptation to endophytic lifestyles under semi-arid conditions. Beyond their taxonomic novelty, the isolates exhibited in vitro traits associated with plant adaptation and stress tolerance, including IAA production, ACC deaminase activity, and tolerance to Zn, Cu, and Cd. Genomic analyses further indicated functions related to phosphate acquisition and stress response. These findings expand the taxonomic framework of Achromobacter sp., establish C. colocynthis and P. harmala as reservoirs of novel endophytic bacteria, and highlight their potential relevance for agricultural biotechnology in stress-prone environments. Full article

Cucurbit crops—including cucumber (Cucumis sativus), watermelon (Citrullus lanatus), and melon (Cucumis melo)—are of major economic and nutritional importance worldwide. Yet their productivity and quality are severely compromised by foliar fungal diseases, particularly powdery mildew (PM), downy mildew (DM), and target leaf spot (TLS). While PM and DM have been extensively studied, TLS has emerged as an increasingly prevalent and damaging disease in key production regions, yet it remains comparatively understudied—especially with respect to its molecular basis and comparative pathobiology relative to PM and DM. Current reliance on chemical fungicides is hampered by escalating pathogen resistance and concerns over residual toxicity, whereas conventional breeding approaches face inherent limitations in pyramiding durable, broad-spectrum resistance against multiple pathogens. In this context, cucumber has emerged as a pivotal model species for dissecting foliar disease resistance mechanisms in cucurbits, supported by a high-quality reference genome, extensive resequencing datasets, diverse germplasm collections, and an efficient Agrobacterium-mediated transformation system. Despite these advantages, existing reviews predominantly address PM or DM resistance in isolation; comprehensive syntheses integrating TLS resistance advances—and critically, cross-disease comparisons of genetic architecture, transcriptional reprogramming, and defense signaling—are notably scarce. Furthermore, the translational pipeline—from gene discovery and functional validation to deployment in marker-assisted or genome-edited breeding—lacks systematic evaluation. Here, we provide a focused, cucumber-centered review that (i) synthesizes recent progress in mapping QTLs and GWAS loci, and characterizing key resistance-associated gene families (such as NLRs, RLKs, PR genes) conferring resistance to PM, DM, and TLS; (ii) integrates transcriptomic, epigenomic, and proteomic evidence to delineate conserved versus pathogen-specific host responses; (iii) highlights breakthroughs and unresolved questions in TLS resistance research, including the roles of novel susceptibility factors and non-canonical immune regulators; and (iv) critically assesses bottlenecks in translating resistance genes into practical breeding outcomes—such as linkage drag, functional redundancy, and genotype-by-environment interactions—and proposes empirically grounded strategies for accelerating molecular design of multi-disease-resistant cultivars. Collectively, this review aims to bridge fundamental insights with applied breeding goals, offering a conceptual and strategic framework for integrated management of foliar fungal diseases and the development of durable, broad-spectrum resistance in cucurbits. Full article

Plant architecture is a critical agronomic trait in watermelon (Citrullus lanatus), with vine length directly influencing planting density, light interception, and field management efficiency. Short-vine forms have become important agronomic targets in breeding due to their advantages of high-density planting, efficient light utilization, and simplified field management. In this study, a dwarf mutant, designated PKH207, was identified from an ethyl methanesulfonate (EMS)-mutagenized population of the watermelon inbred line G42. The mutant exhibited significantly reduced plant height and shortened internodes due to decreased cell expansion in stem tissues. Genetic analysis indicated that the dwarf phenotype in PKH207 is controlled by a single recessive gene, which was named Cldw2 (Citrullus lanatus dwarf mutant 2). Using a population of 558 F₂ plants, bulked segregant analysis sequencing (BSA-seq) and linkage mapping delimited the causal locus to a 540.6 kb region on chromosome 10. Within this interval, a single-nucleotide polymorphism (SNP) mutation was identified in the gene ClG42_10g0100600, encoding an α-tubulin, and this gene was determined to be the candidate gene for the dwarf phenotype. Transcriptome analysis revealed that this mutation significantly disrupts key biological processes, including cell wall biosynthesis, microtubule cytoskeleton organization, and auxin signaling pathways, contributing to the dwarfism phenotype. This study identifies a novel dwarfing allele in cucurbits and provides a direct molecular target for breeding compact watermelon cultivars suited to high-density production. Full article

Background: C2H2 zinc finger proteins (C2H2-ZFPs) are one of the largest transcription factor families in plants and play vital roles in plant organ development and patterning, seed germination, and fruit ripening, as well as responses to biotic and abiotic stresses. Although widely studied in many species, the genome-wide characterization of the C2H2-ZFP family in watermelon (Citrullus lanatus) remains lacking. Methods: In this study, we identified 96 ClZFP genes in the watermelon genome and analyzed their chromosomal positions, gene structures, conserved motifs, and expression profiles. A tissue-specific expression analysis of 12 representative ClZFP genes revealed diverse and organ-preferential expression profiles, indicating functional differentiation during development. Results: Under abiotic stress treatments, four genes were significantly downregulated under drought, while one gene was strongly induced; six genes were inhibited and three genes were activated under low temperature; and most tested genes were upregulated at 72 h under salt stress, with one gene continuously induced throughout the treatment period. Key ClZFP members such as ClZFP36 and ClZFP72 showed specific and strong induction under drought and salt stress, respectively. Conclusions: These results indicate that ClZFPs may be involved in the tolerance of watermelon to various abiotic stresses. This study not only clarifies the evolutionary and expression characteristics of the ClZFP family in watermelon but also provides candidate genes for the genetic improvement of stress tolerance in cucurbit crops. Full article

Cadmium (Cd) contamination is widely recognized as a major risk factor affecting the security and quality of crop production. Watermelon (Citrullus lanatus) is a globally cultivated fruit that is susceptible to Cd stress. 24-Epibrassinolide (EBR), an active brassinosteroid, is essential for plant growth and abiotic stress responses. However, its protective role in watermelon under Cd stress remains unclear. This study elucidates the physiological and molecular processes underlying EBR-mediated alleviation of Cd toxicity in watermelon seedlings. The results showed that exogenous EBR application effectively mitigated Cd-induced growth inhibition through decreased Cd deposition, reduced the accumulation of reactive oxygen species (ROS), lowered membrane lipid peroxidation, and increased antioxidant capacity in watermelon leaves under Cd treatment. Transcriptome (RNA-Seq) analysis revealed that EBR triggered substantial reprogramming of gene expression patterns, identifying 530 differentially expressed genes (DEGs) in Cd + EBR co-treatment compared with Cd treatment alone, including 204 down-regulated genes and 326 up-regulated genes. These DEGs are vital for controlling several physiological processes, including phenylpropane metabolism, phenylpropanoid biosynthesis, endoplasmic reticulum’s protein production, cell wall organization, and others. Further physiological assays confirmed that EBR increased the activities of PAL and 4CL, the core enzymes driving phenylpropanoid biosynthesis, leading to a significant accumulation of total phenols and flavonoids. Together, the above results give concrete proof of the powerful functions of 24-EBR, acting as an enhancer of plant performance under Cd stress by enhancing the antioxidant system and by activating the phenylpropanoid pathway and its derived metabolic networks. Full article

Salinization of agricultural areas is one of the main abiotic factors responsible for the reduction of seed germination and vigor. In this context, the use of stress attenuators applied to seeds may contribute to mitigating the effects of salinity and improving the physiological and antioxidant performance of seedlings. This study aimed to evaluate the effects of stress attenuators on the tolerance and antioxidant activity of watermelon Citrullus lanatus (Thunb.) Matsum & Nakai cultivars under saline conditions. The study was conducted in two stages. In the first stage, a 3 × 6 factorial scheme was used to evaluate three salinity levels (0, −0.2, and −0.4 MPa) and six watermelon cultivars. In the second stage, in a 2 × 6 factorial scheme, two cultivars (sensitive and tolerant) were subjected to the combination of salinity (−0.4 MPa) and attenuators: hydropriming, gibberellic acid, salicylic acid, and hydrogen peroxide. Physiological and biochemical traits were evaluated, including hydrogen peroxide content, lipid peroxidation, and the activity of the enzymes, superoxide dismutase, catalase, and ascorbate peroxidase. Salinity reduced germination and seedling vigor, with Crimson Sweet, Charleston Gray, and Charleston Super being the most sensitive cultivars, whereas Congo and Omaru exhibited greater tolerance, and Fairfax also showed good performance under saline conditions. The selection of cultivars for the second stage was based not only on physiological tolerance but also on agronomic and commercial relevance, including post-harvest resistance traits. Seed treatment of Crimson Sweet with salicylic acid and hydrogen peroxide increased antioxidant enzyme activity, with increases of up to 103% in ascorbate peroxidase activity, and reduced oxidative damage, with reductions of 44% in hydrogen peroxide and 49% in malondialdehyde levels. In Fairfax, gibberellic acid contributed to osmotic adjustment, promoting increase of up to 76% in total soluble sugars, while pre-germinative treatment with salicylic acid and hydrogen peroxide promoted higher enzyme activity, contributing to the reduction of oxidative stress. Full article

This study presents a comprehensive multi-objective optimization of sewage wastewater treatment using bio-based coagulants, guided by the Grey Wolf Optimizer (GWO) and its multi-objective variant (MOGWO). Experimental coagulation data, employing Citrullus lanatus and Cucumis melo as natural coagulants, were modeled using multivariate regression techniques, yielding high coefficients of determination (R² > 0.95) across key water quality parameters. The optimization process targeted maximal reductions in turbidity, total suspended solids (TSS), biochemical oxygen demand (BOD), and chemical oxygen demand (COD) through strategic manipulation of pH and coagulant dosage. The single-objective GWO achieved significant outcomes, including a 96.68% turbidity reduction at pH 5 and 50 mg/L dosage. The MOGWO algorithm identified Pareto-optimal solutions, such as a 94.2% turbidity reduction at pH 5 and 72 mg/L dosage, and a balanced BOD reduction of 52.7% at pH 7. The predictive models indicated that optimal treatment conditions could reduce chemical usage by up to 90% compared to conventional coagulants, resulting in potential cost savings of up to 30%. Moreover, the algorithms demonstrated rapid convergence, averaging 200 iterations, highlighting their computational efficiency and robustness. These findings illustrate that integrating bio-based coagulants with advanced optimization techniques can achieve high treatment efficiency while reducing chemical inputs, thus directly supporting environmental sustainability by minimizing sludge and secondary pollution. In this situation, the wastewater treatment plant will focus on resource-recovery systems with less or no waste at the end of the treatment process. This approach aligns with circular economy principles by promoting eco-friendly, cost-effective wastewater treatment solutions suitable for resource-limited settings. The study offers a forward-looking pathway for environmentally responsible wastewater management practices that significantly reduce chemical dependency and contribute to pollution mitigation efforts. Full article