ABSTRACT. The genus Theobroma found in the Amazon region is composed of 22 species, including Theobroma speciosum, better known as cacauí. These species are constantly threatened by forest fragmentation caused by human activities and require conservation strategies and management aimed at preserving them in their natural environments. The main objective of this study was to analyze the population structure and genetic diversity within and between natural populations of T. speciosum by using ISSR molecular markers to understand the population structure of the species. Four natural populations belonging to the Amazon rainforest (BAC, CRO, FLA, and PNA), located in the State of Mato Grosso, were selected. Amplification reactions were performed using 15 ISSR primers. A total of 101 loci 3511 Genetic diversity in Theobroma speciosum©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 13 (2): 3510-3519 (2014) were found, of which 54.46% were polymorphic at the species level. The BAC population showed higher genetic diversity (H = 0.095 and I = 0.144) and higher percentage of polymorphism (28.71%). The populations showed an F ST value of 0.604, indicating marked genetic differentiation. The highest genetic variation was found between populations. Gene flow was low between populations, indicating genetic isolation between populations.

ABSTRACT. The genus Theobroma, recently reclassified in the family Malvaceae, comprises some species with high economic potential, including the cupuí, Theobroma subincanum Mart., which has not yet been domesticated, and whose genetics and population structure are mostly unknown. This study aimed to assess the population structure and genetic diversity in natural populations of T. subincanum Mart., using inter-simple sequence repeat (ISSR) markers. A total of 59 individuals were sampled in three geographically separate populations, CFA, CMN, and CPT. Nei's genetic distance was estimated to characterize populations with the use of 13 polymorphic primers. The analysis of 4999 ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 12 (4): 4998-5006 (2013) Genetic diversity in Theobroma subincana Mart. molecular variance revealed that the variability between populations (51.71%) was higher than that within populations (48.29%). Among the three populations, CPT showed the highest diversity index and percentage of polymorphism. The ISSR molecular markers were efficient and presented sufficient polymorphism to estimate genetic diversity in populations of T. subincanum Mart.

The present study was carried out in a native Brazil nut tree population (Bertholletia excelsa Bonpl., Lecythidaceae) to assess its genetic diversity and structure. Ten microsatellite markers were used to genotype 198 adult trees (B. excelsa). The population presented high genetic diversity and inbreeding absence rates. The empirical Bayesian method showed three distinct groups in the structure of this population. Molecular analysis of variance showed 98% variability within groups, and 2% between groups. The genetic divergence (F) indicated little difference between groups; thus, suggesting efficient gene flow between the analyzed B. excelsa adult trees.

individual trees. Results evidenced that mating was not random due to self-fertilization, to mating between related trees and correlated mating, and families comprised different relatedness levels such as half-sibs, full-sibs, self-sibs and self-half-sibs; some cases, mating presented inbreeding. These results were addressed to discuss strategies for seed collection applied to conservation ex situ, tree breeding and environmental reforestation.

Recebido em março/2017; Aceito em agosto/2017. RESUMO:O estudo objetivou analisar a diversidade genética de Theobroma speciosum e Theobroma subincanum em um fragmento florestal no município de Alta Floresta, Mato Grosso, Brasil. Foram amostrados aleatoriamente 21 indivíduos T. speciosum e 20 de T. subincanum. Sete primers ISSR foram utilizados e produziram 35 fragmentos dos quais 42,8% apresentaram polimorfismo para T. speciosum e 57,1% para T. subincanum. A diversidade genética de Nei e o Índice de Shannon foram de 0,133 e 0,201 para T. speciosum e 0,244 e 0,351 para T. subincanum respectivamente. O dendrograma UPGMA apresentou quatro grupos para T. speciosum e três grupos para T. subincanum. Os marcadores ISSR foram capazes de acessar a diversidade das duas espécies em estudo gerando informações para programas de conservação e melhoramento genético e demonstraram que a fragmentação vegetal ocasionou um efeito maior sobre a diversidade genética da espécie T. speciosum nas populações estudadas. Os níveis de diversidade encontrados no estudo indicam existência de variabilidade genética e alertam para a importância da conservação in situ destas populações como fonte de genes para o melhoramento genético do gênero Theobroma. Palavras-chave: Cacauí. Cupuí, fragmentação florestal, ISSR.Genetic diversity of two species of Theobroma L. in a forest fragment in Amazon Portal, MT, Brazil ABSTRACT:This study aimed to analyze the genetic diversity of Theobroma speciosum and Theobroma subincanum in forest fragment in the municipality of Alta Floresta, Mato Grosso, Brazil. We randomly sampled twenty-one T. speciosum individuals and twenty T. subincanum individuals. The seven ISSR primers used produced 35 fragments, from which 42,8% were polymorphic for T. speciosum and 57,1 % were polymorphic for T. subincanum. The Nei's genetic diversity and Shannon index respectively were 0,133 and 0,201 for T. speciosum and 0,244 and 0,351 for T. subincanum. The UPGMA dendrogram showed four clusters for T. speciosum and three clusters for T. subincanum. The ISSR markers were able to access the genetic diversity of the two species studied, thus they provided information for conservation and breeding programs, also demonstrated that forest fragmentation caused a greater effect on genetic diversity of the T. speciosum species in the populations studied. The levels of diversity found in the study indicate that there is genetic variability and alert to the importance of in situ conservation of these populations as a source of genes for the genetic improvement of the genus Theobroma.