Assessment of Cucurbita spp. Peel Extracts as Potential Sources of Active Substances for Skin Care and Dermatology.

By-products of cultivated plants are one of the major environmental concerns worldwide. Due to the high concentration of bioactive chemicals, such waste may be considered hazardous due to the interference with the plant growth, deterioration of the drinking water quality or toxic effects on sensitive marine organisms. Moreover, plant-derived by-products, with proper handling, may represent a low-cost source of bioactive compounds potentially important for pharmaceutical and cosmetics industries. The aim of the study was to evaluate the phytochemical composition, antioxidant activity, the influence of tyrosinase activity, in vitro sun protecting factor and cytotoxicity of 15 extracts from peels of five cultivars of Cucurbita maxima and C. moschata. The extracts were prepared using "green solvents" (water, 50% propylene glycol, and 20% ethanol) and ultrasound-assisted extraction. The performed analysis showed that the peel extracts from various cultivars differ significantly in respect to the phytochemical content and activity. The type of solvent also had a significant impact on the extract's composition and bioactivity. Aqueous peel extracts contained the highest amounts of flavonoids, showed the greatest antioxidant potential and the most significant in vitro SPF values. In vitro studies showed that the analyzed peel extracts are not cytotoxic for human keratinocytes up to the concentration of 1000 µg/mL and thus might be considered as non-irritant for the skin. The study confirms the potential application of peel extracts from Cucurbita spp. cultivars in cosmetic products.

Anther Culture in Cucurbita Species.

Production of homozygous pure parental lines is the first stage of hybrid vegetable breeding. Unfortunately, producing pure lines takes a long time by classical breeding methods, especially in open-pollinated vegetable species, and this period can be up to 8-10 years. Recently, doubled haploid (DH) technology, as a set of biotechnological methods, has emerged as an alternative to classical breeding methods and allows for the generation of 100% homozygous pure double haploid lines in 1 or 2 years. Although haploid plants were successfully produced via irradiated pollen technique and gynogenesis in some Cucurbita species, haploid plants have not been obtained from some lines due to genotype dependency, and haploidy frequency is still not sufficient for use in a breeding program. Thus, anther culture technique has emerged as an alternative technique in the DH process. The main objective of this chapter is to provide explanatory information on anther culture technique applied in the Cucurbita genus. For this purpose , key points and details of methods and protocols of the anther culture technique are described in summer squash (Cucurbita pepo L.), pumpkin (Cucurbita moschata Duch.), and winter squash (Cucurbita maxima Duch.).

Gynogenesis in Cucurbita Species.

The development of F1 hybrid vegetable varieties emerges as a result of a great effort, long time, investment, knowledge, and advanced technology. The first stage of hybrid vegetable breeding is obtaining pure lines. It is possible to obtain homozygous parent lines used in the production of hybrid varieties with traditional breeding methods. This period takes 8-10 years, especially in some vegetables which are highly open-pollinated, such as Cucurbita spp. Androgenetic- and/or gynogenetic-based dihaploidization methods provide 100% homozygous pure haploid lines in 1-2 years and save time and effort.The DH frequency by irradiated pollen technique and anther culture strongly depends on the genotypic response, whereby their practical use in a breeding program is still limited. As a possible alternative technique, gynogenesis (unfertilized ovule/ovarium cultures) switches on to produce haploid plants in some Cucurbita species. In the Cucurbita genus, gynogenesis has been one of the most studied and popular DH techniques and presented remarkable results in recent years.

Induction of Parthenogenesis by Irradiated Pollen in Cucurbita Species.

Due to their many superior agronomic traits (high yield and fruit quality, resistance/tolerance to biotic and abiotic stress factors, etc.), hybrid vegetable cultivars are widely used in vegetable production all over the world. The first stage of hybrid vegetable breeding is to obtain homozygous pure parental lines. Unfortunately, producing pure lines takes a long time by classical breeding methods, especially in open-pollinated vegetable species, and this period can be up to 8-10 years. Recently, doubled haploid (DH) technology, as a biotechnological method, has emerged as an alternative to classical breeding methods and allows for the generation of pure (100% homozygous) DH lines in one or two years.However, the DH technique needs labor-intensive efforts and experiences as well as the use of appropriate production technologies. The main objective of this chapter is to provide explanatory information on the technique of induction of parthenogenesis by irradiated pollen applied to several species of the Cucurbita genus. For this purpose , key points and details of methods and protocols of this technique are described in summer squash (Cucurbita pepo L.), pumpkin (Cucurbita moschata Duch.), and winter squash (Cucurbita maxima Duch.).

Assessment of genetic diversity of pumpkins (Cucurbita spp.) from western Kenya using SSR molecular markers.

Pumpkins (Cucurbita spp.) are among most neglected and underutilized crops cultivated for food and medicine. The major constraint to pumpkin production is lack of genetically improved seeds. The current study was aimed at evaluating the genetic diversity of pumpkins from eight counties in western Kenya using five SSR markers. Seeds were extracted from pumpkin fruits, dried and planted on plastic trays for 4 weeks. DNA was isolated from young leaves using CTAB method and amplified. The samples were genotyped using an ABI 3730 genetic analyzer and the allelic data analyzed using Power Marker V 3.25, DARwin V 6.0.12 and GenAIEx V 6.41software. The five SSR loci were polymorphic with a total of 33 alleles and a mean PIC value of 0.534. The gene diversity and observed heterozygosity was 0.796-0.329 and 0.967-0.164, respectively. Most of genetic variations were found within and among individual samples rather than among counties, with samples of some counties having private alleles. Based on the inbreeding coefficient (F), there was outbreeding in pumpkins from Kakamega county (F = - 0.282) and inbreeding in pumpkins from Kisii, Bungoma and Nyamira counties (F = 0.500, 0.409 and 0.286 respectively). The findings of this study suggest that genetic variation and distribution of pumpkins in western Kenya was due to monocropping and intercropping farming systems, trading of pumpkins in markets and exchange of seeds among local farmers rather than geographical and climatic differences.

Crop domestication facilitated rapid geographical expansion of a specialist pollinator, the squash bee Peponapis pruinosa.

Squash was first domesticated in Mexico and is now found throughout North America (NA) along with Peponapis pruinosa, a pollen specialist bee species of the squash genus Cucurbita The origin and spread of squash cultivation is well-studied archaeologically and phylogenetically; however, no study has documented how cultivation of this or any other crop has influenced species in mutualistic interactions. We used molecular markers to reconstruct the demographic range expansion and colonization routes of P. pruinosa from its native range into temperate NA. Populations east of the Rocky Mountains expanded from the wild host plant's range in Mexico and were established by a series of founder events. Eastern North America was most likely colonized from squash bee populations in the present-day continental Midwest USA and not from routes that followed the Gulf and Atlantic coasts from Mexico. Populations of P. pruinosa west of the Rockies spread north from the warm deserts much more recently, showing two genetically differentiated populations with no admixture: one in California and the other one in eastern Great Basin. These bees have repeatedly endured severe bottlenecks as they colonized NA, following human spread of their Cucurbita pollen hosts during the Holocene.

Striped Cucumber Beetle (Coleoptera: Chrysomelidae) Aggregation in Response to Cultivar and Flowering.

The striped cucumber beetle [Acalymma vittatum (F.)] is a specialist pest of cucurbits throughout its range in the United States and Canada. Improved integrated pest management options are needed across the pest's range, especially on organic farms where there are few effective controls. Trap cropping in cucurbits is an option, but there are significant challenges to the technique. Because cucurbit flowers are highly attractive to the beetles, four field experiments tested whether cultivar and phenology interact to preferentially aggregate beetles. The first experiment tested the hypothesis that cucurbit flowers were more attractive to striped cucumber beetles than was foliage. The second experiment tested whether there were differences in beetle aggregation between two relatively attractive cultivars. The third and fourth experiments were factorial designs with two plant cultivars and two levels of flowering to specifically test for an interaction of cultivar and flowering. Results indicated that flowers were more attractive than foliage, beetle aggregation was affected by plant cultivar, and that there was an interaction of cultivar with flowering. We conclude that a single cultivar may be sufficient to serve as a generic trap crop to protect a wide variety of cucurbits.

Reação fenotípica de genótipos de abóboras ao vírus da mancha anelar do mamoeiro, estirpe melancia (Pappaya ringspot virus, strain watermelon ­ PRSV-W) / Phenotypic reaction of Cucurbita spp. genotypes to Pappaya ringspot virus, watermelon strain ­ PRSV-W

O Pappaya ringspot vírus, estirpe melancia - PRSV-W, é a principal doença virótica das abóboras em condições tropicais. O trabalho objetivou avaliar a resistência fenotípica e o padrão de sintomas apresentados por genótipos de abóboras (Cucurbita spp.) ao PRSV-W. O experimento foi conduzido no delineamento inteiramente casualizado com quatro repetições e 10 plantas por parcela. Foram realizadas duas inoculações, a primeira na fase cotiledonar e a segunda cinco dias após a primeira. As plantas foram avaliadas quanto ao aparecimento de sintomas durante 30 dias, começando 10 dias após a segunda inoculação, através de uma escala de notas, em que: nota ­ 1: plantas com folhas sem sintomas de mosaico e; nota ­ 5: plantas com folhas apresentando mosaico intenso, com bolhosidade e presença de deformações foliares mais severas. Foram avaliados nove genótipos, dos quais três são regionais [ABTO#01 e ABTO#02 (C. maxima); ABTO#03 (C. moschata)]; e seis são cultivares comerciais [cv. Caserta (C. pepo); cvs. Menina Brasileira; Paulista; Baianinha; Jacarezinho (C. moschata); e o híbrido interespecífico Tetsukabuto ou Kabutiá (C. máxima x C. moschata)]. Também foram avaliadas progênies endogâmicas do acesso ABTO#01. Apenas o genótipo regional ABTO#01 não apresentou sintomas durante o período de avaliação, sendo considerado resistente. Todos os genótipos comerciais foram suscetíveis e os sintomas apresentados foram bolhosidades, mosaicos, estreitamento foliar e subdesenvolvimento. Todas as progênies endogâmicas oriundas do acesso ABTO#01 avaliadas foram resistentes ao PRSV-W e, portanto, constituem progênies promissoras para serem utilizadas em programas de melhoramento genético da abóbora para a região do Tocantins.

The Pappaya ringspot virus, watermelon strain - PRSV-W is the most important viral disease of Cucurbita spp. in the tropical conditions. The study evaluated the phenotypic resistance and the pattern of symptoms presented by the genotypes of Cucurbita spp. to PRSV-W. The experiment was conducted in completely randomized design with four replications. The plants were evaluated for symptoms 30 days after inoculation, using a scale where: Note - 1: plants with no symptoms of mosaic and; note - 5: plants with leaves showing mosaic intense with blistering and the presence of more severe leaf deformation. Nine genotypes were evaluated, three landraces [ABTO#01; ABTO#02 (C. maxima) e ABTO#03 (C. moschata) and six commercial cultivars [cv.Caserta (C. pepo); cvs. Menina Brasileira; Paulista; Baianinha; Jacarezinho (C. moschata) and the interspecific hybrid Tetsukabuto or Kabutiá (C. moschata x C. maximum)]. Inbred progenies from ABTO#01 were also evaluated. All commercial genotypes were susceptible and symptoms were blistering, mosaics, leaf narrowing and underdevelopment. The genotype ABTO#01 and their inbred progeny presented no virus symptoms during the evaluation period, being considered resistant and a promising genotype to be used in breeding programs of the Cucurbita spp. aiming resistance to PRSV-W.