Tropical fruit trees are an important component of the human diet; however, little is known about their genetic diversity levels. Zapote mamey (Pouteria sapota) is a tree native to southeastern Mexico and Central America, and Mexico is the leading producer in the world. Studies of the genetic diversity of Zapote mamey have been based on cultivated materials using morphological and biochemical characterization or dominant molecular markers. To gain a deeper understanding about the conservation status of Zapote mamey in its center of origin and domestication, we collected 188 individuals from eight wild and five cultivated populations in southeastern Mexico and characterized them using eight microsatellite loci. STRUCTURE, 3D-PCoA, and neighbor-joining analyses showed three groups in the wild gene pool and one group in the cultivated gene pool. F ST values were significant between wild and cultivated gene pools, among the four groups observed and among the 13 populations collected (0.13, 0.25, and 0.36, respectively). Overall, we found low levels of genetic diversity (A = 2.77, H O = 0.29, H E = 0.39), permutation tests did not show significant differences between wild and cultivated gene pools. The Garza-Williamson index showed low values in both gene pools (wild = 0.16, cultivated = 0.11) and the Bottleneck program indicated a decrease in genetic diversity in both gene pools (wild, P = 0.027; cultivated, P = 0.054); both analyses suggest a potential genetic bottleneck within this species. This study can help to generate adequate sampling techniques and to develop effective management strategies for Zapote mamey of southeastern Mexico.

Background: Understanding the genetic structure of wild relatives of domesticated species is crucial for its conservation and to elucidate the sites of crop domestication. Lima bean is one of the five domesticated Phaseolus species and Mexico is one of its centers of domestication. Recent studies showed the existence of two wild gene pools (MI and MII) of this species in Mexico and suggested that their genetic divergence occurred in southeast Mexico. Question: Did MI and MII groups diverged around the Isthmus of Tehuantepec, Mexico? Studied species: Lima bean: Neotropical plant species, herbaceous, with an annual/short life cycle and with autogamous tendency. Study site and years of study: Seven wild populations were collected in 2012 in the State of Chiapas, México, area underrepresented in previous studies. Methods: Genetic diversity and grouping patterns of collected populations and their relationship to MI and MII groups were analyzed at eight microsatellite loci. Results: High genetic structure (F ST : 0.42 to 0.96) and a high level of genetic diversity (H E = 0.48) were found. The analyses, and presence of admixed populations in MI and MII, suggested that the genetic divergence of these groups is an ongoing process centered around the Isthmus of Tehuantepec. Conclusions: Our results support the hypothesis that MI and MII groups diverged around the Isthmus of Tehuantepec; however, sampling should be increased both at population and genomic levels, to determine the precise organization of the genetic diversity of wild P. lunatus from Mexico. Keywords: Genetic diversity, Genetic resources, Lima bean, Microsatelites, SSR markers, Wild relatives. Diversidad y diferenciación genética de las poblaciones silvestres de Phaseolus lunatus de Chiapas, México, y sus relaciones genéticas con los grupos MI y MII ResumenAntecedentes: Entender la estructura genética de los parientes silvestres de las especies domesticadas es crucial para su conservación y para elucidar los sitios de domesticación de los cultivos. El frijol Lima es una de las cinco especies domesticadas del género Phaseolus y México es uno de sus centros de domesticación. Estudios recientes señalaron dos acervos genéticos silvestres (MI y MII) en México y sugirieron que su divergencia ocurrió en el sureste de México. Pregunta: ¿Los grupos silvestres MI y MII divergieron alrededor del Istmo de Tehuantepec, México? Especie en estudio: El frijol Lima es una especie Neotropical, herbácea, con ciclo de vida anual/corto y tendencia autógama. Sitio y años de estudio: Siete poblaciones silvestres fueron colectadas en 2012 en el Estado de Chiapas, México, área que fue subrepresentada en estudios previos. Métodos: Se analizó la diversidad genética y los patrones de agrupamiento de las poblaciones colectadas y su relación con los grupos MI and MII, usando ocho loci de microsatélites. Resultados: Se encontró una estructura genética alta (F ST : 0.42 a 0.96) y niveles altos de diversidad gené-tica (H E = 0.48). Los análisis y la presencia de poblaciones mezclada...

Objective: The objective of this study was to morphologically characterize mamey in 10 municipalities of the Sierra Nororiental of Puebla (Totonacapan Poblano), Mexico. Design/methodology/approach: In the study, 206 accessions obtained from simple random sampling using qualitative and quantitative morphological descriptors were evaluated, using an analysis of variance, principal components and hierarchical cluster analysis with the Gower distance and the Ward grouping method. Results: Quantitative descriptors had high coefficients of variability (12.66% to 43.40%). The principal components analysis indicated that components 1 (41.66%), 2 (19.97%) and 3 (16.62%) accounted for 78.25% of the variance and the cluster analysis identified eight groups; the tree and leaf variables turned out to be the most important to group the samples. Limitations on study/implications: For greater accuracy on the morphological diversity of mamey, it is necessary to include more descriptors of the fruit and the flower. Findings/conclusions: The descriptors that contributed the most to the grouping were those related to the shape, height and size of the tree, and the weight, size and shape of the leaf; in relation to the fruit, the descriptor that contributed the most was the shape. These results could be useful in programs of conservation, improvement, and use of the mamey.