Platonia insignis Mart. (Clusiaceae) is widespread throughout the Amazon and adjacent areas. The fruits (known locally as "bacuri") have significant commercial potential, but the species is under threat from agro-industrial expansion. The genetic variability within 72 genotypes of P. insignis belonging to ten populations collected in the Brazilian states of Maranhão and Piauí, and maintained in the germplasm collection of Embrapa Meio-Norte, has been determined, and the organization of genetic diversity within populations, between populations and among geographic groups verified. Eighteen selected inter simple sequence repeat primers allowed amplification of 236 loci of which 221 (93.64%) were polymorphic, indicating a high level of genetic diversity. At the population level, the Shannon and Nei diversity indices ranged from 0.082 to 0.323 and from 0.120 to 0.480, respectively. The global coefficient of genetic differentiation (G(ST)) was 0.4730 indicating that differentiation between populations was significant, a finding that was confirmed by analysis of molecular variance (Φ(ST) = 0.28). UPGMA cluster analysis revealed that the genotypes could be stratified into groups that were well defined and consistent with those identified in the dendrogram constructed using pair wise Φ(ST) values. The high genetic diversity established in this study may facilitate the management and conservation of the germplasm of P. insignis.
Este trabalho teve como objetivo avaliar as características físicas e químicas de frutos de bacuri coletados de plantas matrizes de ocorrência na região Meio-Norte. As características analisadas foram: comprimento, largura e peso médio de fruto; peso médio de polpa; relação comprimento/largura, espessura de casca; percentagem de casca; percentagem de polpa; percentagem de sementes; número de sementes/fruto; número de secção partenocárpica/fruto; teor de sólidos solúveis totais; acidez total titulável e relação sólidos solúveis totais/acidez total titulável. Os frutos foram coletados de 26 plantas matrizes de bacuri mapeadas em nove locais de coleta no Piauí e Maranhão. Efetuou-se a avaliação das características físicas e químicas no Laboratório de Fisiologia Vegetal da Embrapa Meio-Norte, em Teresina-PI, utilizando-se de amostras de frutos de tamanho variável em função da disponibilidade de produção. Foi evidenciado o efeito significativo de local de coleta e de matrizes para todas as características estudadas, à exceção do número de secção partenocárpica/fruto para o qual não houve efeito de local de coleta. As características peso médio de fruto e peso médio de polpa; peso médio de fruto e largura de fruto; peso médio de polpa e largura de fruto; comprimento de fruto e espessura de casca; comprimento de fruto e percentagem de casca; espessura de casca e percentagem de casca, e peso médio de fruto e comprimento de fruto apresentaram altos valores de correlações fenotípicas (rP > ou = 0,85). Estimativas de repetibilidade, variando de 0,50 (percentagem de polpa) a 0,98 (acidez total titulável), indicaram ampla variabilidade das características analisadas em relação ao efeito do ambiente permanente.
ABSTRACT. We evaluated genetic variability of mango (Mangifera indica) accessions maintained in the Active Germplasm Bank of Embrapa Meio-Norte in Teresina, Piauí, Brazil, using RAPDs. Among these accessions, 35 originated from plantings in Brazil, six from the USA and one from India. Genomic DNA, extracted from leaf material using a commercial purification kit, was subjected to PCR with the primers A01, A09, G03, G10, N05, and M16. Fifty-five polymorphic loci were identified, with mean of 9.16 ± 3.31 bands per primer and 100% polymorphism. Application of unweighted pair group method using arithmetic average cluster analysis demonstrated five genotypic groups among the accessions examined. The genotypes Rosa 41, Rosa 48 and Rosa 49 were highly similar (94% similarity), whereas genotypes Sensation and Rosa 18 were the most divergent (only 7% similarity). The mango accessions were found to have considerable genetic variability, RAPD analysis of the genetic diversity of mango germplasm demonstrating the importance of analyzing each genotype in a collection in order to efficiently maintain the germplasm collection.
ABSTRACT. The arboreal species Spondias mombin L. (Anacardiaceae) is widely distributed in Brazil, where the fruits, known by the common name of cajá, are an important commercial commodity. We evaluated genetic variability among 32 cajá accessions of the Germplasm Collection of Embrapa Meio-Norte using RAPD technique. Reaction conditions for efficient RAPD amplifications were optimized in preliminary tests, and primers were selected from a set designed by the University of British Columbia on the basis of high levels of polymorphism and adequate band resolution. The 21 primers employed in the final analysis produced 145 fragments, 79% of which were polymorphic. Based on the RAPD data, a dendrogram was constructed using the unweighted pair group method with arithmetic mean clustering technique. The 32 cajá accessions were classified into three main groups with a mean genetic similarity of 68.8%. Group I comprised 26 accessions (74.1% similarity), and group II included five accessions (74.0% similarity), while group III consisted of one accession (BGC 06), which exhibited the lowest similarity coefficients. Accessions BGC 06 and BGC 31 were the most unrelated and, hence, most suitable for initial crossings in order to obtain high levels of segregation. We concluded, based on the repeatability and reproducibility tests, that the RAPD technique is reliable and efficient for revealing the genetic diversity of cajá accessions, which will be useful for genetic improvement programs.
Some species of Anacardium (Anacardiaceae) produce fruits and pseudofruits that are smaller than those of the common cashew (Anacardium occidentale) and, for this reason, are known collectively in Brazil as "cajuí". Despite their economic value in the food market and their important environmental and ecological functions, cajuí trees remain underexploited. We employed nine inter-simple sequence repeat (ISSR) markers to characterize two presupposed populations of cajuí comprising 25 accessions maintained in the germplasm bank of Embrapa Meio-Norte (Teresina, PI, Brazil). Population structure and relationships between accessions were determined in order to generate knowledge that could contribute to genetic improvement programs and better management of this germplasm bank. A high degree of polymorphism (91.3%) was observed among the accessions. Analysis of molecular variance and Bayesian analysis demonstrated that the two presupposed populations were not genetically differentiated but constituted a single population containing highly diversified individuals including migrants, ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 17 (4): gmr18212 A.N.C. Borges et al. 2 migrant descendants and possible hybrids. Nonetheless, genetic variability within the accessions could be organized into two distinct, but linked, groups that had undergone extensive exchange of genetic material, as verified by the high gene flow index (= 13.145). The substantial genetic variability observed could be attributed to individual differences between accessions rather than to differential spatial distribution. This report enhances our knowledge of the genus Anacardium and should facilitate the future improvement of cajuí culture and fruit quality. In addition, our study highlights the importance of further taxonomic studies on the species of Anacardium that comprise cajuí.
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