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The African citrus psyllid, Trioza erytreae (Del Guercio) (Hemiptera: Triozidae), is a vector of Candidatus Liberibacter africanus (CLaf), a pathogen that causes huanglongbing (HLB) in Africa. Trioza erytreae has invaded areas of Asia and Europe and has threatened citrus production due to its biological habits and the transmission of CLaf. Mexico is a country where citrus production has a vital role from the economic and social point of view. Therefore, ecological niche modeling (ENM) was used to determine if Mexico has the environmental availability that will allow T. erytreae invasion. We analyzed whether or not the distribution of Casimiroa edulis La Llave (Rutaceae) in the country could be a factor that enables the dispersal of T. eytreae. The environmental connectivity between five points of entry into the country (two ports and three airports) was explored to determine possible routes of dispersal of T. erytrae. The results showed that Mexico has wide availability for the invasion of the African citrus psyllid, which coincides with essential citrus areas of the country and with the distribution of C. edulis. Of the entry points studied, the Port of Veracruz showed nearby areas with environmental connectivity. Preventive monitoring measures for T. erytreae in Mexico should focus on Veracruz state because it has an entry point, ideal environmental availability, citrus areas, and specimens of C. edulis.

Agricultural production systems based on the application of synthetic chemical inputs are changing to more ecological management systems. In this context, rhizosphere microorganisms are considered fundamental to improving soil fertility and providing protection to the host plant. The objective of this study was to perform co-inoculation of Sechium edule (Jacq.) Sw. plants (chayote) with Rhizophagus intraradices and Azospirillum brasilense to reduce Phytophthora capsici damage. The chayote seeds were established in bags, and their inoculation was evaluated alone and in combination with R. intraradices and A. brasilense, in addition to inoculating the stem 14 days after planting with P. capsici. Eight treatments were distributed completely at random, with four repetitions. Morphological and physiological yield variables were recorded at 28, 56, and 84. It was found that S. edule treatment with R. intraradices and A. brasilense increased dry matter allocation in the morphological and physiological performance components. The biomass of plants inoculated with P. capsici and biofertilized with R. intraradices and A. brasilense decreased by 27%, which is relevant, since, under field conditions, plants infected with P. capsici die. Petiole biomass and leaf area decreased during the three evaluation periods with the presence of P. capsici. The other components had a differential response.

Mangifera indica var Ataulfo is the main variety grown in the Soconusco region of Chiapas, Mexico and faces a decrease in firmness and weight loss due to hydrothermal treatment, in addition to non-uniform ripening and consequently a decrease in price as the harvest period lengthens. In order to improve the postharvest quality of the “Ataulfo” mango fruit, preharvest applications of aminoethoxyvinylglycine (AVG; ReTain®, a.i. 15%) were carried out in “La Norteña” with Phaeozem soil, 1500 mm of annual precipitation, and applications of agrochemicals, and in “Santa Cecilia” with Acrisol soil, 2500 mm of annual precipitation, and without agrochemicals. The treatments were: (1) Control, (2) One application 7 days before harvest (0.1 g L−1), (3) Two applications (14 days and 7 days before harvest, 0.2 g L−1) and (4) Three applications (21, 14 and 7 days before harvest, in total 0.3 g L−1), with completely randomized design in the laboratory. The results show contrasting differences between the evaluation sites, with lower weight loss (18.4%) and 3.1% more firmness in a drier climate and higher soil calcium content. The average firmness (N) on day 14 was 18.3 and with three applications of AVG it was 22.0. The °Brix at the end of the study in the control was 11.3 and on average with AVG applications it was 14.4. Three-time applications of AVG in preharvest delayed the weight loss with an increase in the maintenance of the firmness of the fruits. The weight of the fruit epidermis was lower with AVG applications, and increased with the number of applications.

The Sechium edule Perla Negra cultivar is a recently-obtained biological material whose progenitors are S. edule var. nigrum minor and S. edule var. amarus silvestrys, the latter of which has been reported to have antiproliferative activity against the HeLa P-388 and L-929 cancer cell lines. The present study aimed to determine if the methanolic extract of the fruit of the Perla Negra cultivar had the same biological activity. The methanolic extract was phytochemically characterized by thin layer chromatography (TLC) and column chromatography (CC), identifying the terpenes and flavonoids. The compounds identified via high performance liquid chromatography (HPLC) were Cucurbitacins B, D, E, and I for the terpene fractions, and Rutin, Phlorizidin, Myricetin, Quercetin, Naringenin, Phloretin, Apigenin, and Galangin for the flavonoid fractions). Biological activity was evaluated with different concentrations of the methanolic extract in the HeLa cell line and normal lymphocytes. The methanolic extract inhibited the proliferation of HeLa cells (IC50 1.85 µg·mL−1), but the lymphocytes were affected by the extract (IC50 30.04 µg·mL−1). Some fractions, and the pool of all of them, showed inhibition higher than 80% at a concentration of 2.11 µg·mL−1. Therefore, the biological effect shown by the methanolic extract of the Perla Negra has some specificity in inhibiting tumor cells and not normal cells; an unusual feature among molecules investigated as potential biomedical agents.

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.

Sechium edule (Jacq.) Sw. (Cucurbitaceae) is a species native to Mexico and Central America. The collection, characterization, and evaluation of accessions maintained in genebanks is essential for the conservation of this species. However, there are no specific varietal descriptors that differ from those used in a phenetic approach and are adapted to international registration guidelines to help distinguish, improve, cluster, and protect intraspecific variants of common use and those obtained by breeding. Therefore, 65 morphological descriptors (qualitative and quantitative) were evaluated in 133 accessions obtained from Mexico, Guatemala, and Costa Rica located in the National Germplasm Bank of S. edule in Mexico. These characteristics were observed to be phenetically stable for five generations under the same agroclimatic conditions. In addition, an analysis of amplified fragment length polymorphism (AFLP) was applied to 133 samples from a set of 245 accessions. According to the multivariate analysis, 26 of the 65 descriptors evaluated (qualitative and quantitative) enabled differentiation of varieties of S. edule. The AFLP analysis showed a high level of polymorphism and genetic distance between cultivated accessions and their corresponding wild ancestor. The variations in S. edule suggest that the morphological characteristics have differentiated from an essentially derived initial edible variety (ancestral original variety), but unlike other cucurbits, there is no evidence of the ancestral edible for Sechium since the seed is unorthodox and there are no relicts.

Mangifera indica var Ataulfo is the main variety grown in the Soconusco region of Chiapas, Mexico and faces a decrease in firmness and weight loss due to hydrothermal treatment, in addition to non-uniform ripening and consequently a decrease in price as the harvest period lengthens. In order to improve the postharvest quality of the “Ataulfo” mango fruit, preharvest applications of aminoethoxyvinylglycine (AVG; ReTain[sup.®], a.i. 15%) were carried out in “La Norteña” with Phaeozem soil, 1500 mm of annual precipitation, and applications of agrochemicals, and in “Santa Cecilia” with Acrisol soil, 2500 mm of annual precipitation, and without agrochemicals. The treatments were: (1) Control, (2) One application 7 days before harvest (0.1 g L[sup.−1]), (3) Two applications (14 days and 7 days before harvest, 0.2 g L[sup.−1]) and (4) Three applications (21, 14 and 7 days before harvest, in total 0.3 g L[sup.−1]), with completely randomized design in the laboratory. The results show contrasting differences between the evaluation sites, with lower weight loss (18.4%) and 3.1% more firmness in a drier climate and higher soil calcium content. The average firmness (N) on day 14 was 18.3 and with three applications of AVG it was 22.0. The °Brix at the end of the study in the control was 11.3 and on average with AVG applications it was 14.4. Three-time applications of AVG in preharvest delayed the weight loss with an increase in the maintenance of the firmness of the fruits. The weight of the fruit epidermis was lower with AVG applications, and increased with the number of applications.

Sechium edule (Jacq.) Sw. (Cucurbitaceae) is a species native to Mexico and Central America. The collection, characterization, and evaluation of accessions maintained in genebanks is essential for the conservation of this species. However, there are no specific varietal descriptors that differ from those used in a phenetic approach and are adapted to international registration guidelines to help distinguish, improve, cluster, and protect intraspecific variants of common use and those obtained by breeding. Therefore, 65 morphological descriptors (qualitative and quantitative) were evaluated in 133 accessions obtained from Mexico, Guatemala, and Costa Rica located in the National Germplasm Bank of S. edule in Mexico. These characteristics were observed to be phenetically stable for five generations under the same agroclimatic conditions. In addition, an analysis of amplified fragment length polymorphism (AFLP) was applied to 133 samples from a set of 245 accessions. According to the multivariate analysis, 26 of the 65 descriptors evaluated (qualitative and quantitative) enabled differentiation of varieties of S. edule. The AFLP analysis showed a high level of polymorphism and genetic distance between cultivated accessions and their corresponding wild ancestor. The variations in S. edule suggest that the morphological characteristics have differentiated from an essentially derived initial edible variety (ancestral original variety), but unlike other cucurbits, there is no evidence of the ancestral edible for Sechium since the seed is unorthodox and there are no relicts.

In order to identify the influence of Rhizophagus intraradices in yield, content of N and P in vegetable tissue and corn H-560 grain in interaction with different rates of fertilization, the present was established in a medium fertility soil with sandy-loam texture. Five treatments were: control, R. intraradices, [120.sub.N]-[60.sub.P], R. intraradices + [120.sub.N]-[60.sub.P], R. intraradices + [80.sub.N]-[40.sub.P] and R. intraradices + [40.sub.N]-[40.sub.P], in randomized block design with four repetitions. R. intraradices was adhered to the seed with carboxymethyl cellulose at a concentration of 40 spores/g of soil and 95% of colonization in the host plant. Nitrogen was applied (50%) at sowing and the rest twenty days later, and the phosphorus all at sowing. The experimental unit consisted of six rows of 0.90m wide and 5m long. Irrigation by gravity was performed every ten days, during the winter 2014. Morphological and physiological variables of yield were determined: percentage of radical colonization every 14 days and content of N and P at 42 days in flag leaf and grain to harvest. The results indicate that R. intraradices colonizes widely the root system of the corn from the initial stages of its development and promotes greater growth and performance in interaction with the chemical fertilization, allowing, in addition, to diminish the latter without detriment of the yield. The symbiosis between R. intraradices and corn increased the concentration of N and P in plant tissue and grain.

Con la finalidad de identificar la influencia de Rhizophagus intraradices en rendimiento, contenido de N y P en tejido vegetal y grano del maíz H-560 en interacción con dosis de fertilización bajo riego, se estableció el presente estudio en un suelo de mediana fertilidad con textura migajón-arenosa. Cinco tratamientos fueron aplicados: testigo, R. intraradices, 120N-60P, R. intraradices + 120N-60P, R. intraradices + 80N-40P y R. intraradices + 40N-40P, en diseño de bloque al azar con cuatro repeticiones. R. intraradices fue adherido a la semilla con carboximetil celulosa a una concentración de 40 esporas/g de suelo y 95% de colonización en la planta huésped. El nitrógeno se aplicó el 50% a la siembra y el resto veinte días después, y el fósforo todo a la siembra. La unidad experimental fueron seis surcos a 0,90m de ancho por 5m de largo. Se regó por gravedad cada diez días, durante el invierno 2014. Se determinaron variables morfológicas y fisiológicas del rendimiento: porcentaje de colonización radical cada 14 días y contenido de N y P a los 42 días en hoja bandera y en grano a cosecha. Los resultados indican que R. intraradices coloniza ampliamente el sistema radical del maíz desde las etapas iniciales de su desarrollo y promueve mayor crecimiento y rendimiento en interacción con las dosis de fertilización química, permitiendo, además, disminuirlas sin detrimento del rendimiento. La simbiosis entre R. Intraradices y maíz incrementó la concentración de N y P en el tejido vegetal y en el grano.