Phenotypic and molecular assessment of genetic structure and diversity in a panel of winged yam (Dioscorea alata) clones and cultivars.

A better understanding of the structure and extent of genetic variability in a breeding population of a crop is essential for translating genetic diversity to genetic gain. We assessed the nature and pattern of genetic variability and differentiation in a panel of 100 winged-yam (Dioscorea alata) accessions using 24 phenotypic traits and 6,918 single nucleotide polymorphism (SNP) markers. Multivariate analysis for phenotypic variability indicated that all phenotypic traits assessed were useful in discriminating the yam clones and cultivars. Cluster analysis based on phenotypic data distinguished two significant groups, while a corresponding analysis with SNP markers indicated three genetic groups. However, joint analysis for the phenotypic and genotypic data provided three clusters that could be useful for the identification of heterotic groups in the D. alata breeding program. Our analysis for phenotypic and molecular level diversity provided valuable information about overall diversity and variation in economically important traits useful for establishing crossing panels with contrasting traits of interest. The selection and hybridization of parental lines from the different heterotic groups identified would facilitate maximizing diversity and exploiting population heterosis in the D. alata breeding program.

Distribution, management and diversity of the endangered Amerindian yam (Dioscorea trifida L.).

The objective of this study was to verify the occurrence of Dioscorea trifida in Brazil and to obtain information concerning its distribution, management and diversity. Farmers from 21 communities were interviewed in the states of São Paulo, Santa Catarina and Mato Grosso. During the visits, semi-structured interviews were conducted to collect socio-economic, management and diversity data for this crop. Fifty-one collected accessions, plus two accessions obtained at local markets of Amazonas, were characterized using 12 morphological traits. Most the interviewed farmers were men (75%) with a mean age of 59.5 years. Just a few young people and labor force were available for agricultural activities, with an average of only three individuals per farm. Most farmers (56%) grew only one variety of D. trifida, although 44% had more than one variety in their fields, which aims to provide greater assurance at harvest. Many popular names were observed for D. trifida, and cará roxo (purple yam) was the name most used by farmers (43.4%). Characters referring to the tuber, such as skin and flesh color, were most relevant for the distinction of the accessions. The results of this study may collaborate to develop strategies for conservation, both ex situ and in situ, within the view of on farm conservation.

Distribution, management and diversity of the endangered Amerindian yam (Dioscorea trifida L.) / Distribuição, manejo e diversidade da espécie ameaçada de inhame ameríndio (Dioscorea trifida L.)

The objective of this study was to verify the occurrence of Dioscorea trifida in Brazil and to obtain information concerning its distribution, management and diversity. Farmers from 21 communities were interviewed in the states of São Paulo, Santa Catarina and Mato Grosso. During the visits, semi-structured interviews were conducted to collect socio-economic, management and diversity data for this crop. Fifty-one collected accessions, plus two accessions obtained at local markets of Amazonas, were characterized using 12 morphological traits. Most the interviewed farmers were men (75%) with a mean age of 59.5 years. Just a few young people and labor force were available for agricultural activities, with an average of only three individuals per farm. Most farmers (56%) grew only one variety of D. trifida, although 44% had more than one variety in their fields, which aims to provide greater assurance at harvest. Many popular names were observed for D. trifida, and cará roxo (purple yam) was the name most used by farmers (43.4%). Characters referring to the tuber, such as skin and flesh color, were most relevant for the distinction of the accessions. The results of this study may collaborate to develop strategies for conservation, both ex situ and in situ, within the view of on farm conservation.

O objetivo deste trabalho foi verificar a ocorrência de Dioscorea trifida no Brasil e obter informações a respeito da sua distribuição, manejo e diversidade. Para tanto, foram visitados e entrevistados agricultores de 21 comunidades, nos Estados de São Paulo, Santa Catarina, Mato Grosso. Durante as visitas, foram realizadas entrevistas semi-estruturadas visando obter dados sócioeconômicos, de manejo e diversidade da cultura. Cinquenta e um acessos, além de dois acessos adquiridos em feiras no Estado do Amazonas, foram caracterizados por meio de 12 descritores morfológicos. A maioria dos entrevistados era homem (75%) com média de idade de 59,5 anos. Observou-se um número reduzido de jovens e mão de obra disponível para as atividades agrícolas, cerca de três indivíduos por roça. A maior parte dos agricultores (56%) cultiva apenas uma variedade de D. trifida, embora 44% tenham declarado o cultivo de mais de uma variedade, procedimento que visa dar maior garantia de colheita. Vários nomes populares foram observados para D. trifida, sendo cará roxo, a denominação mais utilizada pelos agricultores (43,4%). Os caracteres referentes às túberas, como cor da casca e da polpa, foram os mais relevantes para a distinção dos acessos. Os resultados obtidos poderão colaborar para elaborar estratégias de conservação, tanto ex situ como in situ, dentro da visão de conservação on farm.