Diversidade genética entre acessos de cacau de fazendas e de banco de germoplasma na Bahia

Abstract

Resumo -O objetivo deste trabalho foi avaliar a diversidade genética de acessos de cacau, selecionados previamente como produtivos e resistentes à vassoura-de-bruxa na Bahia, e estudar suas inter-relações com genótipos no banco de germoplasma. Amostras de DNA de folhas dos 120 acessos, coletados em 17 fazendas de sete municípios do Sul da Bahia, foram amplificadas pela técnica de RAPD ("random amplified polymorphic DNA"). Os coeficientes de dissimilaridade genética, calculados pelo método de Jaccard a partir das bandas RAPD, permitiram evidenciar, pela análise de agrupamento, que a maioria das seleções das fazendas (89,2%) agrupou-se com acessos do banco de germoplasma considerados representativos da diversidade de cacau (híbridos, trinitários, Scavinas, amazônicos e cacau-comum). As demais seleções distribuíram-se em outros sete grupos distintos. Há elevada diversidade genética entre as seleções das fazendas, e algumas delas devem ter-se originado de genitores não incluídos nesta análise. Esses materiais apresentam potencial para seleção de clones com maior diversidade para novos cruzamentos ou uso pelos agricultores.Termos para indexação: Theobroma cacao, marcador molecular, melhoramento genético, vassoura-de-bruxa. Genetic diversity among farm and germplasm bank accessions of cacao in Bahia, BrazilAbstract -The objective of this work was to assess genetic diversity of farm cacao accessions, previously selected as productive and resistant to witch broom in Bahia, Brazil, and to study their interrelationship with reference genotypes on germplasm bank. DNA samples from 120 cacao accessions, collected on 17 farms in seven counties in Southern Bahia, were amplified by RAPD technique (random amplified polymorphic DNA). The coefficients of genetic dissimilarity, calculated from the RAPD bands by Jaccard method, allowed to show by cluster analysis that most farm selections (89.2%) grouped with accessions from germplasm bank considered representatives of the cacao genetic diversity (hybrids, Trinitarian, Scavina, Amazon and common cacao). The other selections were distributed in seven distinct groups. There is high genetic diversity among farm selections, and some of them may have originated from other progenitors not included in this analysis. These materials present potential for clone selection with higher diversity for new crossings or direct use by agriculturists.

Genetic molecular diversity, production and resistance to witches' broom in cacao clones

“…Upon analysis of a larger sample from the region's farms, it was verified that there are materials with agronomic and disease-resistant characteristics that are genetically distant from Sca6 (Leal et al 2008). This demonstrated that clonal varieties selected in commercial areas for their resistance remain unknown when it comes to their genetic diversity and productive potential, for the purpose of being used in genetic improvement, revealing the need for further studies involving materials from different areas of the Bahia cacao productive region.…”

Genetic diversity in yellow passion fruit (Passiflora edulis Sims) based on RAPD

“…In these studies a variable number of polymorphic bands was observed, for example, 30 polymorphic bands by Leal et al (2008) and 231 polymorphic bands obtained and evaluated by Ferrão et al (2009). Variation in the number of RAPD markers used in diversity studies is also demonstrated and discussed by Dias et al (2004).…”

“…The application of RAPD markers is not restricted to the characterization of the genus Passiflora and the use efficiency of this technique in different genetic approaches is demonstrated by recent results in solving problems in different plant species, generating useful information for conservation and genetic improvement of plants (Juchum et al 2007, Leal et al 2008, Ferrão et al 2009). In these studies a variable number of polymorphic bands was observed, for example, 30 polymorphic bands by Leal et al (2008) and 231 polymorphic bands obtained and evaluated by Ferrão et al (2009).…”

Genetic diversity in sugar apple (Annona squamosa L.) by using RAPD markers

“…PCR-based molecular techniques provide a variety of DNA markers for diversity analysis (Newbury & Ford-Lloyd, 1993), identification of cultivars (Matsumoto & Fukui, 1996), gene localization, and construction of linkage maps (Giovanni et al, 2004). RAPD markers have been used for diversity analysis in cacao (Leal et al, 2008), banana (Souza et al, 2008) and, sugar apple (Bharad et al, 2009, Ahmad et al, 2010.…”