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Species distribution models identify regions with ideal environmental characteristics for the establishment and proliferation of species. The chayote ( Sechium edule ) is a crop that originated and domesticated in Mexico; however, it is cultivated in different parts of the world due to its nutritional and pharmaceutical importance. The objective of this research was to locate the potential distribution of S. edule in Japan supported on seven machine learning models, to also determine which bioclimatic variables influence its distribution, and which are the most suitable regions for its establishment. Thirty-one occurrence points, elevation, and the bioclimatic variables bio1, bio3, bio4, bio7, bio8, bio12, bio14, bio15, and bio17 were used to infer the models. Hundred percent of the occurrence points coincided with the Cfa climate distributed in Acrisol (60.9%), Andosol (17.4%), Cambisol (13%), Fluvisol (4.35%), and Gleysol (4.35%) soil. The maximum entropy model (Maxent) model reported the highest area under the curve (AUC) value (0.93), while the generalized linear model (GLM) obtained the best true skills statistics (TSS) value (0.84); the super vector machine (SVM) model reported the largest suitability area ≥ 0.5 with 100,394.4 km 2 . Temperature-related variables were the major contributors to the models and the ones explaining the distribution limits of S. edule in Japan. The coastal eastern prefectures of Kantō, Chūbu, Kinki, Chūgoku, Kyūshū, and Shikoku regions showed a suitability ≥ 0.5.

The genus Sechium P. Br. (Cucurbitaceae) includes ten species, two of which are edible. The inedible genotypes are in a fragile ecological niche, since they are not used by rural inhabitants. A rescue and genetic crossing program was designed to identify uses that favor their conservation due to their content of bioactive secondary metabolites (Sm) for health. Fruits of S. compositum (wild type), hybrid H-D Victor (inedible), and S. edule var. nigrum spinosum (edible) were evaluated by extraction methods such as juice and oven drying to determine the yields of Sm, with in vivo evaluations of liver damage. The dried biomass (40 °C) extracted with ethanolic and methanolic procedures showed lower Sm content than the juice (fresh biomass). More than 90% of phenolic acids and cucurbitacins in the extracts were degraded, possibly due to the drying time (oven). Biological activity showed that nigrum spinosum and HD-Victor have fewer toxic metabolites than S. compositum. The hybrid H-D Victor is of reduced cytotoxicity, showing the advantages of hybridization with wild types. Phytochemical and biological activity characterization may contribute to the conservation of genotypes and become a source of bioactive natural products.

In this study, we investigated how increasing temperature affects tomato fruit physicochemical traits and looked for genetic variability to help maintain fruit quality in the context of climate change. High temperature (HT: +3 °C) was applied at four fruit developmental stages, from anthesis and 15, 30 or 45 days after anthesis until ripening to three genotypes, a commercial cultivar (Money Maker, “MM”) and two genotypes likely more tolerant to HT (Campeche 40 “C40”, a landrace from a warm, humid region, and a hybrid Chapingo F1, “F1”, resulting from crossbreeding landraces tolerant to high temperature). Increasing average diurnal temperature (from 27.0 to 29.9) reduced fruit firmness and size and affected fruit composition according to genotype. Sugar and acid contents were highly impacted in MM and C40 fruits, especially when HT was applied during the rapid fruit growth period. The application of HT at different fruit developmental stages revealed that HT could enhance acid accumulation and degradation (rate and/or duration), resulting in different effects on fruit acidity between genotypes. The F1 genotype appeared to be more adapted to HT, producing larger fruits with higher sugar, lower acid and increased vitamin C and calcium content. These results provide interesting directions for breeding programs that want to maintain future tomato fruit yields and quality.

The chayote fruit is a nontraditional vegetable belonging to the Cucurbitaceae family. The fruit has an endocarpic recalcitrant seed that emerges postharvest, drastically shortening its shelf life. In this study, the changes during fruit and seed development before and after harvest (ah) are reported. Additionally, in order to investigate how growth regulators (GRs) affect seed germination, 2-cloroethylphosphonic acid (CPA) (200 µL L−1), gibberellic acid (GA3) (100 and 200 mg L−1), auxin (2,4-D) (0.5 and 1.0 mM), and abscisic acid (ABA) (0.5 and 1.0 mM) were applied after harvest. The results showed that the chayote fruit reached horticultural maturity at 21 days after anthesis, with a sigmoid trend: phase I featured slow growth and high transpiration; in phase II, growth was accelerated and accumulation of endosperm was observed; and in phase III, both growth rate and transpiration were reduced, soluble sugars increased, and the seed showed 25% cotyledon development. At day 13 ah, CPA, GA3, and 2,4-D (0.5 mM) increased seed germination, with values between 10 and 15 mm of the embryonary axis, and the treatments with 2,4-D (1 mM) and ABA (0.5 and 1.0 mM) retarded their growth (2–6 mm). This research allowed us to reveal the phenological phases and the shelf life of the chayote fruit, as well as the results of possible postharvest treatment with GRs; our results suggest that strategies to delay viviparism and prolong the shelf life of the fruit should be applied before 10 days ah, when the embryonic axis of the seed has not developed.

Fruits of chayote [Sechium edule (Jacq.) Swartz] are a non-traditional vegetable widely consumed in Latin America, with the state of Veracruz, México being the world’s main producer, but little is known about the nutraceutical potential. This study aimed to determine the chemical compositions and antioxidant activities from the juice fruits from two commercial varieties of chayote cultivated in Mexico, as well as a proposal for the elaboration of chayote juices with stevia leaves and pineapple juice. The physicochemical properties of juice from virens levis (VL) and nigrum spinosum (NS) varieties were determined using standard methods. The juice of the two varieties differ significantly regarding the concentrations of total soluble solids and total sugars, but not vitamin C. The total concentration of phenolics in NS extracts was slightly higher than in VL (1005 and 856 mg 100 g−1 dry-weight, respectively), but the total flavonoid contents were similar (27 and 26 mg 100 g−1 dry-weight, respectively). Cucurbitacin D was predominant in both varieties. The radical scavenging capacities of VL and NS extracts varied slightly (IC50 = 0.45 to 0.65 mg mL−1), while the antioxidant activities were similar (~80%). The NS variety is particularly promising regarding nutraceutical application. The chayote juice combined with stevia and pineapple maintained the original nutraceutical characteristics of the fruit, but enhanced the organoleptic characteristics like density and sugar/acidity balance.