Cucurbit Seeds Research Articles

Biochemical Composition of Pumpkin Seeds and Seed By-Products.

The goal of the current work was to assess the nutritional profile and phytochemical properties of cucurbit (Cucurbita maxima L.) seeds, seed oils and oil extraction by-products (e.g., seed-cakes). Our results suggest a high nutritional value for both cucurbit seeds and cucurbit cake, while γ-tocopherol was the richest compound, with traces of α, β and δ-tocopherol compounds also detected. Regarding the free sugars composition, there were recorded significant statistical differences between seeds and cucurbit seed-cake, although sucrose content was the highest for both matrices (1.97 and 2.9 g/100 g dw, respectively) followed by trehalose (0.26 and 0.25 g/100 g dw, respectively), fructose (0.20 and 0.34 g/100 g dw, respectively) and glucose (0.21 and 0.19 g/100 g dw, respectively). In terms of organic acids, oxalic was the only compound detected in seed cake (0.006 g/100 g dw), while in seeds only traces of oxalic and malic acid were detected. In relation to fatty acid composition, linolenic acid was the most abundant compound in both seeds and seed-cake (43.9% and 41.5%, respectively), while oleic acid (37.0% and 36.3%, respectively), palmitic acid (12.2% and 14.0%, respectively) and stearic acid (4.83% and 5.46%, respectively) were detected in lesser amounts. Moreover, polyunsaturated fatty acids (PUFA) were the major fatty acids class (44.5% and 42.3% in seeds and seed cake, respectively) compared to monounsaturated fatty acids (MUFA; 37.4% and 36.7% in seeds and seed cake, respectively) and saturated fatty acids (SFA; 18.1% and 21.0% in seeds and seed cake, respectively) which were detected in lower amounts. Furthermore, the tested extracts did not present any cytotoxic or hepatoxic activity at the maximum tested concentration (GI50 > 400 μg/mL), while seed oils presented satisfactory antimicrobial properties with inhibitory activity against the studied bacterial strains and fungi. Our findings provide valuable knowledge regarding the exploitation of pumpkin seeds and seed by-products as valuable natural sources of nutrients and phytochemicals in the food industry sector within the context of a circular economy.

Archaeobotanical evidence supports indigenous cucurbit long-term use in the Mesoamerican Neotropics

The squash family (Cucurbitaceae) contains some of the most important crops cultivated worldwide and has played an important ecological, economic, and cultural role for millennia. In the American tropics, squashes were among the first cultivated crop species, but little is known about how their domestication unfolded. Here, we employ direct radiocarbon dating and morphological analyses of desiccated cucurbit seeds, rinds, and stems from El Gigante Rockshelter in Honduras to reconstruct human practices of selection and cultivation of Lagenaria siceraria, Cucurbita pepo, and Cucurbita moschata. Direct radiocarbon dating indicates that humans started using Lagenaria and wild Cucurbita starting ~ 10,950 calendar years before present (cal B.P.), primarily as watertight vessels and possibly as cooking and drinking containers. A rind directly dated to 11,150–10,765 cal B.P. represents the oldest known bottle gourd in the Americas. Domesticated C. moschata subsequently appeared ~ 4035 cal B.P., followed by domesticated C. pepo ~ 2190 cal B.P. associated with increasing evidence for their use as food crops. Multivariate statistical analysis of seed size and shape show that the archaeological C. pepo assemblage exhibits significant variability, representing at least three varieties: one similar to present-day zucchini, another like present-day vegetable marrow, and a native cultivar without modern analogs. Our archaeobotanical data supports the hypothesis that Indigenous cucurbit use started in the Early Holocene, and that agricultural complexity during the Late Holocene involved selective breeding that encouraged crop diversification.

Design and Implementation of the Positioning and Directing Precision Seeder for Cucurbita Ficifolia Seeds

Highlights Identification of large seed plantule point direction were realized using machine vision. A large seed orientation seeder is designed to achieve automatic orientation seeding of large seeds. The directional seeding success (deflection angle of less than 15°) rate was 92.89%. The qualified rate of positioning and orientation reached 87.80% Abstract. A consistent plantule point and a uniform distribution of cucurbit seeds are required for factory seedlings and grafting. However, precision sowing Cucurbita ficifolia seeds automatically with a positioning and orientation method is difficult due to their large, non-spherical shape. To overcome this challenge, a machine vision-based precision seeder was designed specifically for Cucurbita ficifolia seeds. To achieve consistent seed placement and orientation at a 45° angle, a method using machine vision and precise seed positioning and orientation has been proposed. The plantule point location was determined by comparing the pixel values at both ends of seed. The positioning and orientation module was developed to achieve seeding with same orientation of plantule point and located in the center of the plug tray. Finally, the positioning and orientation precision seeder for seeds were tested and evaluated. The results showed that the accuracy rate of seed plantule point identification and the success rate of the seeds orientation actuator were 97.56% and 100.00%. 95.21% of seeds achieved a deflection angle of less than 15°. The germination port of 96.06% of the seeds is distributed in a circle with the center of the hole as the center and a radius of 10 mm. The qualified rate of positioning and orientation reached 87.80%, and the sowing efficiency was about 3750 grains/h. The results showed that the seeder achieves the consistent orientation of the germination port of seeds and sows the seeds in the center of the hole. This finding provides technical support for seedling testing and large-scale factory seedlings. Keywords: Cucurbita ficifolia seeds, Machine vision, PLC control, Positioning and orientation, Precision seeder.

Further Molecular Diagnosis Determines Lack of Evidence for Real Seed Transmission of Tomato Leaf Curl New Delhi Virus in Cucurbits.

Begomoviruses (family Geminiviridae) cause serious diseases in many crop families. Since 2013, the Spanish isolate of tomato leaf curl New Delhi virus (ToLCNDV) has been a limiting factor for cucurbits production in the Mediterranean basin, forcing farmers to adapt new management and control techniques. Although it is well-known that begomoviruses are naturally transmitted by the whitefly Bemisia tabaci, the capacity of these viruses to be vertically transmitted through seeds remains controversial. Clarifying the potential ToLCNDV seed transmission is essential to understand the epidemiology of this threating-for-cucurbits virus and to design appropriate control strategies. We assessed ToLCNDV distribution in the leaves, flowers and seeds of the infected plants of susceptible Cucumis melo accessions and toleration to the infected genotypes of Cucurbita moschata by conventional and quantitative PCR. We analyzed whether the viral particle was transmitted to offspring. We also evaluated ToLCNDV presence in commercial seeds of cucurbits (zucchini (Cucurbita pepo), melon (C. melo), cucumber (Cucumis sativus) and watermelon (Citrullus lanatus)) and in their progenies. As the assayed seedlings remained symptomless, we increased the reliability and accuracy of detection in these samples by searching for replicative forms of ToLCNDV by combining Southern blot hybridization and rolling-circle amplification (RCA). However, integral genomic DNA was not identified in the plants of offspring. Although the seedborne nature of ToLCNDV was confirmed, our results do not support the transmission of this virus from contaminated seeds to progeny.

Genome Characterisation of the CGMMV Virus Population in Australia-Informing Plant Biosecurity Policy.

The detection of cucumber green mottle mosaic (CGMMV) in the Northern Territory (NT), Australia, in 2014 led to the introduction of strict quarantine measures for the importation of cucurbit seeds by the Australian federal government. Further detections in Queensland, Western Australia (WA), New South Wales and South Australia occurred in the period 2015-2020. To explore the diversity of the current Australian CGMMV population, 35 new coding sequence complete genomes for CGMMV isolates from Australian incursions and surveys were prepared for this study. In conjunction with published genomes from the NT and WA, sequence, phylogenetic, and genetic variation and variant analyses were performed, and the data were compared with those for international CGMMV isolates. Based on these analyses, it can be inferred that the Australian CGMMV population resulted from a single virus source via multiple introductions.

A Comparative Study on the Nutritional, Antioxidant, Thermal, Morphological and Diffraction Properties of Selected Cucurbit Seeds

Cucurbit seeds are highly nutritious but generally discarded as a waste by various processing sectors. This study aims to investigate the nutritional profile of seeds of ash gourd, pumpkin, watermelon and musk melon. The techniques, such as mineral, vitamin, amino acid and fatty acid profiling, will provide the nutritional status of the selected seed samples, while the antinutritional accounts will assess the safety of the food application. The thermal behavior of the seeds will guide the decision of the food application of the selected seeds. These seeds were found to be rich in protein and fat, minerals, vitamins and amino acids. The antinutritional compounds in the studied seeds were within the safety limits. Ash gourd seeds had the highest antioxidant activity at 85.11%, with the highest values of total phenols at 176.07 mg GAE/100 g and flavonoids at 159.16 mg QE/100 g. The peaks of the functional group at 3008 cm−1, 1651 cm−1, 1528 cm−1 and 1233 cm−1 denote the presence of polyunsaturated fatty acids, and amide I, II and III, respectively. The thermal analysis of the seeds reviled that the seeds were thermally stable and could be used in product development. The surface morphology was attributed to the interaction of fat, protein and carbohydrates. The semicrystalline or amorphous nature of the seeds resulted in an A-type pattern in the XRD analysis. The results obtained here supports the food application of the selected seeds.

Preparation and physicochemical properties of cucurbit protein isolate from Lagenaria siceraria defatted seed flour

Cucurbit seeds including Lagenaria siceraria seeds have been used from early times as a source of food. The protein constitutes about thirty-five percent of the weight of the decorticated seeds. Isolates are defined as the kind of protein that forms with a high concentration of protein that contains no dietary fiber. This study aims to investigate the preparation of protein isolated from Lagenaria siceraria defatted seed flour and to study their physicochemical properties. Protein was isolated from seed flours by using distilled water, salt solution, an alkaline solution, then precipitated with 0.1 N hydrochloric acid followed by centrifugation and freeze-drying. The findings reflected a high protein content (ranged from 80.67-91.04 g 100g-1) with the absence of fats. The functional properties of the protein isolate are said to be acceptable exhibiting a considerable range for all examined properties, water holding capacity 2.4-3.9 mL g-1 protein, fat binding ability 2.7-3.7 mL g-1 protein, emulsion capacity 51.0-57.8 mL of oil per g of protein, and bulk density 0.39-0.56 g mL-1, for all samples. The results of foaming stability indicated that the seeds were possibly utilized in food applications such as beverages and cakes processing. The maximum protein solubility (95%) occurred at the alkaline range pH 10 and11. The SDS page test detected that the three major polypeptides are those with molecular weights 10, 23, and 38 KDa. This study is the first to take place on the protein isolation from eight Lagenaria siceraria defatted seeds grown in Sudan, opening the way for further studies on these seeds

A one-step reverse-transcription loop-mediated isothermal amplification assay optimized for the direct detection of cucumber green mottle mosaic virus in cucurbit seeds

Cucumber green mottle mosaic virus (CGMMV) is a seed-borne virus that causes significant economic losses in farms cultivating cucurbit plants. With the increase in global trade of cucurbit seeds, it is essential to develop a rapid, reliable, and convenient diagnostic method for the direct detection of CGMMV in these seeds for prevention and management of the disease. Here, we developed a one-step reverse-transcription loop-mediated isothermal amplification (RT-LAMP) assay for the direct detection of CGMMV in cucurbit seeds. To improve the efficiency of the one-step RT-LAMP assay, six primers were designed to target the most conserved regions of the gene encoding the movement protein of CGMMV. Our one-step RT-LAMP assay was optimized to improve specificity and sensitivity for CGMMV detection in individual seeds. A comparison of the detection sensitivity revealed that our one-step RT-LAMP assay was 100-fold more sensitive than the current reverse transcription-polymerase chain reaction assay used for CGMMV quarantine in Korea. Collectively, the one-step RT-LAMP assay developed in the present study is appropriate for the direct detection of CGMMV in individual cucurbit seeds.

Viruses in cucurbit seeds from on-line mail-order providers

Seeds of three important cucurbit species (cucumber, melon and zucchini) were obtained through on-line mail-order providers and tested for selected viruses of biosecurity and agronomic concern. One or more of the targeted viruses were detected in 23 of the 31 seed lots tested. The quarantine pest melon necrotic spot virus was detected by ELISA in melon seeds. Multiple instances of contamination with the quarantine pest cucumber green mottle mosaic virus were also detected, and its presence in seeds of all three plant species was confirmed by inoculation and re-isolation from indicator plants. Cucumber mosaic virus, squash mosaic virus and potyviruses were repeatedly detected, and instances of insect pest and plant trash contamination were also observed. Seeds imported into Australia from some on-line sources have potential to introduce organisms of biosecurity concern.

Physiological quality of cucurbits in spectral qualities

The objective of this work was to evaluate the influence of spectral qualities on the germination and vigor of cucurbit seeds. This experiment was a completely randomized design, in a factorial scheme 3 x 6, with three species of cucurbitaceae: cucumber, melon and watermelon. Six spectral qualities were used: blue LED, white LED, red LED, blue + red LED, fluorescent and dark (no light). Variables related to germination and vigor were analyzed. The cucurbitaceae presented differentiated responses when submitted to the different spectral qualities. For cucumber seeds, the luminous spectra increased root length, compared to the dark treatment. The melon seeds had low physiological quality; for these, the dark promoted a higher percentage of germinated and normal seeds. For watermelon seeds, the white LED conditions led to a higher percentage of normal seedlings, high rate of germination (IVG) and lower percentage of dead seeds. Red LED conditioned high IVG in watermelon. In general, fluorescent light favors carotenoid content and the dark condition favors shoot length in cucurbit seeds.

Plant virology: Alive and kicking!

Plant virology: Alive and kicking!

Antimicrobial Activities of Nano Metal Hybrid Materials against the Microorganisms Isolated from Cucurbit Seeds

Antimicrobial Activities of Nano Metal Hybrid Materials against the Microorganisms Isolated from Cucurbit Seeds

Prevalence of Acidovorax citrulli in Commercial Cucurbit Seedlots During 2010-2018 in China.

Acidovorax citrulli is the causal agent of bacterial fruit blotch (BFB), a serious threat to cucurbit fruit and seed production worldwide. In recent years, the BFB has spread to many areas of China, mainly via the inadvertent distribution of contaminated commercial seeds. To assess the prevalence of seedborne A. citrulli in commercial watermelon and other cucurbitaceous seedlots in China, a 9-year survey was conducted between 2010 and 2018. A total of 4,839 seedlots of watermelon and other cucurbitaceous species were collected from 13 major seed production areas of China and tested by a semiselective media-based colony PCR technique for A. citrulli. Overall, A. citrulli was detected in 18.00% (871/4,839) of all cucurbitaceous seedlots. The bacterium was detected in 21.59% (38/176), 19.19% (33/172), 23.44% (214/913), 40.76% (247/606), 13.28% (85/640), 15.40% (95/617), 13.25% (73/551), 8.03% (48/598), and 6.71% (38/566) of all commercial seedlots tested from the 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, and 2018 growing seasons, respectively. Additionally, the prevalence of A. citrulli in cucurbit seedlots was determined for different seed production areas. The prevalence of A. citrulli in cucurbitaceous seedlots produced in Xinjiang, Gansu, Ningxia, Inner Mongolia, and 9 other provinces was 18.76% (582/3103), 26.34% (103/391), 21.47% (82/382), 11.11% (14/126), and 10.75% (90/837), respectively. This is the first survey for A. citrulli in commercial cucurbit seeds in China, and the relatively high prevalence suggests that commercial seeds represent a substantial source of primary inoculum that can threaten cucurbit seed and fruit production in China.

Understanding the Transmissibility of Cucumber Green Mottle Mosaic Virus in Watermelon Seeds and Seed Health Assays.

Cucumber green mottle mosaic virus (CGMMV), an emerging tobamovirus, has caused serious disease outbreaks to cucurbit crops in several countries, including the United States. Although CGMMV is seed-borne, the mechanism of its transmission from a contaminated seed to germinating seedling is still not fully understood, and the most suitable seed health assay method has not been well established. To evaluate the mechanism of seed transmissibility, using highly contaminated watermelon seeds collected from CGMMV-infected experimental plants, bioassays were conducted in a greenhouse through seedling grow-out and by mechanical inoculation. Through natural seedling grow-out, we did not observe seed transmission of CGMMV to germinating seedlings. However, efficient transmission of CGMMV was observed using bioassays on melon plants through mechanical inoculation of seed extract prepared from CGMMV-contaminated seeds. Understanding the seed-borne property and the ease of mechanical transmission of CGMMV from a contaminated seed to seedling is an important finding. In comparative evaluation of various laboratory techniques for seed health assays, we found that enzyme-linked immunosorbent assay and loop-mediated isothermal amplification were the most sensitive and reliable methods to detect CGMMV on cucurbit seeds. Because CGMMV is a seed-borne and highly contagious virus, a new infection might not result in a natural seedling grow-out; it could occur through mechanical transmission from contaminated seeds. Therefore, a sensitive seed health test is necessary to ensure CGMMV-free seed lots are used for planting.

Insights into the maternal pathway for Cucumber green mottle mosaic virus infection of cucurbit seeds.

Cucumber green mottle mosaic virus (CGMMV), genus Tobamovirus, is a major pathogen of cucurbits that primarily affects cucumber, melon, and watermelon crops. The aim of this study was to reveal the contribution of CGMMV-infected female flowers to disease spread. Using a fluorescent in situ hybridization (FISH) technique, we show that ovaries and ovules of CGMMV-infected cucumber and melon plants showed a CGMMV-specific fluorescence signal prior to and following anthesis. The fluorescence signal was prominent but sporadic. Ripe fruits of infected melon plants showed strong signals in the funiculus, the seed stalk, which connects the developing seed to the interior ovary wall. Importantly, in seeds, a strong fluorescence signal was observed in the perisperm-endosperm (PE) envelope, which underlies the seed coat and surrounds the embryo. Interestingly, the fluorescence signal was not uniformly distributed in the PE envelope but was localized to a specific envelope layer. These results have important epidemiological implications for CGMMV management and commercial seed production, particularly regarding the improvement of seed disinfection methods that will contribute to limit the global distribution of the virus.

Improvement of Cucurbit Seed Health Status by Salicylic Acid and Fungicides

Improvement of Cucurbit Seed Health Status by Salicylic Acid and Fungicides

A potential new source: Nutritional and antioxidant properties of edible oils from cucurbit seeds and their impact on human health.

Seeds from the cucurbitaceae plant family are discarded as the byproducts which generally obtained after extraction of oil during food processing. Recently, found a great deal of interest as cucurbit seeds are found to be rich source of nutrients such as monounsaturated fatty acids, polyunsaturated fatty acids, tocopherols (α-Tocopherol, β-Tocopherol, δ-Tocopherol, γ-Tocopherol), carotenoids, β-carotene, phytosterol, proteins, minerals, vitamins, phenolic compounds, and antioxidants. Despite the potential nutritional benefits, the commercial product of cucurbit plants are lacking in the market. Therefore, there is an urgent need to increase production and utilization of cucurbit seed oil for human nutrition. The main purpose of the present review is to sum up the published information on the nutritional potential of cucurbit seed oils to promote industrial production and stimulates further research on commercial use of cucurbit seeds. PRACTICAL APPLICATIONS: The aims of this review are to highlight the nutritional values and antioxidant properties of cucurbit seed and their impact on the overall human health. These cucurbit seeds are rich source of vitamins and minerals which are necessary for healthy human diet. In addition to other commercial oils, cucurbits oils are equally important and rich in essential active ingredients. Quite abundance of cucurbit seeds in African continents can pave way to enhance production on the industrial scale which can create employability ranging from farmers to skilled workers. In all, the oil produced from the cucurbit seeds can be applied practically to implement large-scale production as a part of food industry and dietary supplement industry in paramedical sector.

Rapid and sensitive detection of Acidovorax citrulli in cucurbit seeds by visual loop‐mediated isothermal amplification assay

AbstractA rapid, sensitive and visual loop‐mediated isothermal amplification (LAMP) method for detecting Acidovorax citrulli in cucurbit seed was developed in this study. The LAMP primers were designed to recognize the non‐ribosomal peptide synthetase (NRPS) gene (locus tag: Aave_4658) from A. citrulli. The LAMP assay was conducted at 64°C in 1 hr with calcein as an indicator. The sensitivity and specificity of the LAMP assay were further compared with those of a conventional polymerase chain reaction (PCR). The LAMP assay is highly specific to A. citrulli, and no cross‐reaction was observed with other bacterial pathogen. The sensitivity of the LAMP assay was 100‐fold higher than that of conventional PCR with a detection limit of 1 pg of genomic DNA. Using the LAMP assay, 7 of 12 cantaloupe seedlots collected from Xinjiang province were determined to be positive for A. citrulli. In contrast, only 2 of 12 seedlots showed positive for the pathogen with conventional PCR. Moreover, A. citrulli was detected in 100% of artificially infested seedlots with 0.01% infestation or greater. Our results demonstrated that the LAMP assay was simple, visual and sensitive for detecting A. citrulli, especially in seed health testing. Hence, this method has great potential application in routine detecting seed‐borne pathogens and reducing the risk of epidemics.

Bacterial Seed Endophytes of Domesticated Cucurbits Antagonize Fungal and Oomycete Pathogens Including Powdery Mildew.

The cucurbit vegetables, including cucumbers, melons and pumpkins, have been cultivated for thousands of years without fungicides. However, their seed germination stage is prone to be infected by soil-borne fungal and oomycete pathogens. Endophytes are symbionts that reside inside plant tissues including seeds. Seed endophytes are founders of the juvenile plant microbiome and can promote host defense at seed germination and later stages. We previously isolated 169 bacterial endophytes associated with seeds of diverse cultivated cucurbits. We hypothesized that these endophytes can antagonize major fungal and oomycete pathogens. Here we tested the endophytes for in vitro antagonism (dual culture assays) against important soil-borne pathogens (Rhizoctonia solani, Fusarium graminearum, Phytophthora capsici, Pythium aphanidermatum). The endophytes were also assayed in planta (leaf disk and detached leaf bioassays) for antagonism against a foliar pathogen of global importance, Podosphaera fuliginea, the causative agent of cucurbit powdery mildew. The endophytes were further tested in vitro for secretion of volatile organic compounds (VOCs) known to induce plant defense. Extracellular ribonuclease activity was also tested, as a subset of pathogenesis-related (PR) proteins of plant hosts implicated in suppression of fungal pathogens, displays ribonuclease activity. An unexpected majority of the endophytes (70%, 118/169) exhibited antagonism to the five phytopathogens, of which 68% (50/73) of in vitro antagonists belong to the genera Bacillus and Paenibacillus. All Lactococcus and Pantoea endophytes exhibited anti-oomycete activity. However, amongst the most effective inoculants against Podosphaera fuliginea were Pediococcus and Pantoea endophytes. Interestingly, 67% (113/169) of endophytes emitted host defense inducing VOCs (acetoin/diacetyl) and 62% (104/169) secreted extracellular ribonucleases in vitro, respectively. These results show that seeds of cultivated cucurbits package microbes with significant disease-suppression potential. As seeds can act as vectors for genetic transmission of endophytes across host generations, it is interesting to hypothesize whether humans, when selecting seeds of healthy hosts, may have inadvertently selected for disease-suppressing seed endophytes. As the majority of pathogen-suppressing endophytes belong to Bacillus and Paenibacillus, and since Bacilli are widely used as commercial biocontrol agents of vegetables, we propose that these agents are mimicking the ecological niche established by their endophytic cousins.

Chemical Characterization of Phytochemicals of Cucurbitaceae Family by Gas Chromatography – Mass Spectroscopy

Background: Traditionally plants are being used as an important source of medicines since ancient era. Cucurbit seeds have been used as nutritious snacks as they are rich in phytonutrients and have a wide arena of ethnopharmacological relevance. Keywords: Cucurbita pepo, Cucumis melo, Cucumis sativus, Cucurbit, Mass spectroscopy, γ-Tocopherol.