Abstract:The quantification of genetic diversity and intrapopulation spatial genetic structure (SGS) of tree species are important aspects for in and ex situ conservation practices. In this study we seek to understand the importance of conservation areas by quantifying the genetic diversity and the spatial genetic structure of a natural population of Theobroma speciosum. Within this population, 49 adults and 51 subadults were genotyped for five microsatellite loci. The results showed that adults and subadults have similar levels of genetic diversity and inbreeding (adults: A= 10.4, A e = 10.3, F= 0.68, subadults: A= 10.6, A e = 10.6, F= 0.57). Genetic diversity was spatially structured within the population, and the results suggest that near-neighbor trees up to a distance of 70 m are likely related. SGS is likely the result of short-distance seed dispersal, the short-distance range of pollinators, and infrequent breaches of the self-incompatible mating system. Considering the high demographic density of the species and size of the study area, as well as the high average number of alleles per locus and the presence of rare alleles, we believe that the study population is an excellent resource for in situ genetic conservation of T. speciosum. The study area is also a useful resource for collecting germplasm for ex situ conservation and seed collection, either for breeding programs used in the restoration of degraded areas or forest improvement. Rev. Biol. Trop. 64 (3): 1091-1099. Epub 2016 September 01.Key words: Amazonia, genetic variability, microsatellite markers, cacauhy.The national program of biological diversity, that evaluated and identified priority areas for conservation, sustainable use, and benefitsharing of biodiversity of the Brazilian Amazon, established 27 ecoregions of the Brazilian Legal Amazon (PNJU, 2013). One ecoregion is the Mato Grosso dry forests located in the Northern part of Mato Grosso State. In this area, the Juruena National Park (Parque Nacional do Juruena) was established in 2006 with the aim of protecting endemic Amazonian species. The Conservation Unit (CU) includes headwaters and stretches of important Amazonian rivers, such as Aripuanã, a tributary of the Madeira, Juruena, and Teles Pires Rivers, and tributaries of the Tapajós, and it encompasses an area of significant biogeographical interest. The genus Theobroma occurs naturally in the area.Several species within the Theobroma genus have conventional or potential uses, including Theobroma speciosum Willd. ex Spreng, commonly known as cacauhy. This species is important because it represents a possible source of genetic resistance for other, more economically important species, such as Theobroma cacao (Silva et al., 2011). The fruit rind of T. speciosum is mixed with wood ash to produce a handmade soap that is used in the Amazon and it is an excellent deodorant (Di Stasi & Hiruma-Lima, 2002). In relation to its fatty acids, Gilabert-Escrivá et al. (2002) noted that the composition is very similar to that found in cocoa butter. ...
RESUMO Quinze primers ISSR (entre sequências simples repetidas) foram utilizados para avaliar a diversidade genética entre e dentro de pomares comerciais de
RESUMOO conhecimento anatômico de espécies do gênero Theobroma é importante para o estabelecimento e manutenção de coleções de germoplasma, tendo em vista estudos agronômicos e fitopatológicos e programas de melhoramento genético. Este estudo objetivou caracterizar a anatomia das folhas de Theobroma speciosum, registrando as diferenças estruturais observadas entre folhas de sol e folhas de sombra. Folhas de indivíduos de Theobroma speciosum foram coletadas no Parque Nacional do Juruena e em pastagens na zona rural do município de Alta Floresta -MT. Foram analisados a espessura do mesofilo foliar, dos parênquimas paliçádico e lacunoso, da nervura mediana e do feixe vascular. A análise de agrupamento foi realizada utilizando o método Hierárquico UPGMA, com base na distância euclidiana média padronizada. Foram observados tricomas glandulares do tipo claviforme e estrelados sésseis. A epiderme é unisseriada, o mesofilo é dorsiventral, entretanto os parênquimas são pouco distintos. Feixes vasculares colaterais estão dispersos no mesofilo, formando bainhas que se estendem até as epidermes. A nervura central, em secção transversal, possui formato biconvexo, com sistema vascular fechado envolto por bainha esclerenquimática. A constituição do mesofilo das folhas variou com o ambiente. Plantas expostas a pleno sol apresentam células mais alongadas no parênquima paliçádico, parênquima lacunoso com mais camadas e maior quantidade de tricomas, enquanto que as folhas de sombra apresentaram células com muitos espaços intercelulares no mesofilo. O dendrograma mostrou a formação de dois grupos distintos: o grupo I composto pelas plantas do Parque e o grupo II pelas plantas das pastagens. Tal agrupamento demonstrou alterações anatômicas significativas ocasionadas pelas variações da intensidade luminosa sobre as folhas, o que evidenciou grande capacidade adaptativa de Theobroma speciosum. Palavras-chave: Cacauí; Amazônia; Mesofilo. ABSTRACTThe anatomical knowledge of species of the Theobroma genus is important for the establishment and maintenance of germplasm collections, considering agronomic and phytopathological studies, and breeding programs. This study aimed to characterize the anatomy of Theobroma speciosum leaves, recording the structural differences observed between sun and shade leaves. Theobroma speciosum leaves were collected at Juruena National Park and in pastures in the rural municipality of Alta Floresta -MT. We analyzed the
Abstract:The species Spondias mombin, is native to the Amazonian region. Since these trees' cultivation is incipient, their exploitation is done through extraction techniques. The aim of the present study was to assess the genetic divergences between S. mombin genotypes and to quantify the relative contribution from 12 morphological traits of the species' fruits and seeds, as well as to collect data able to subsidize future research on the species conservation and domestication. 60 genotypes were assessed in total, and ten fruits of each genotype were analyzed. Eight descriptors were used for fruit characterization, namely: fruit mass, pulp weight, volume, length, width, thickness, total soluble solids content and hydrogenionic potential. The seed descriptors were mass, length, width and thickness. The data were assessed through the principal components and groupings by applying the UPGMA and Tocher methods. They were analyzed in the GENES software, based on the dissimilarity matrix (Euclidean distance average). The analysis applied to the principal components showed that the first three components explained 83 % accumulated variation. The main traits contributing to the genotype discrimination were fruit width, fruit pulp weight, pH, seed length and thickness, and the most responsive traits to S. mombin genotype selection. The features fruit mass, seed width, fruit thickness, fruit volume, fruit length, seed mass and total soluble solid content presented the smallest contribution to diversity. The grouping methods UPGMA and Tocher evidenced genetic divergence between the analyzed genotypes. Genotypes 37 and 41 were more divergent than the others, what makes them promising for crossings in future genetic enhancement programs focused on the species' domestication. Rev. Biol. Trop. 65 (4): 1337-1346. Epub 2017 December 01.
Native Theobroma species, such as cacauhy, are losing their habitat due to the intense forest fragmentation in the Amazon region, and preserving their genetic diversity has been the focus of many conservation programs. The aim of the present study is to assess whether fragmentation and habitat reduction affect its genetic structure and lead to genetic diversity losses in natural Theobroma speciosum populations. The study was conducted in two Mato Grosso State (Brazil) locations: Apiacás and Alta Floresta counties. Juruena National Park (JNP) in Apiacás County holds a natural T. speciosum population that has not suffered anthropic influences. A population composed of individuals from three anthropized urban forest parks (UF) in Alta Floresta County was analyzed for comparison. The leaves of 75 T. speciosum individuals distributed in the urban forest fragments and of 100 individuals found in the Juruena National Park were sampled. All nine microsatellite loci showed high polymorphism levels between categories (adults and sub-adults), in both populations. The sub-adult individuals of the fragmented area had a higher value (0.71), and the preserved population, the same value (0.69). The analysis of molecular variance showed 83 % genetic diversity within categories; 16 %, between populations; and only 1 %, between categories. Although the effects were small, a persistent fragmentation process can increase inbreeding and facilitate genetic drift, leading T. speciosum populations to inbreeding depression and loss of diversity. Rev. Biol. Trop. 66(1): 218-226. Epub 2018 March 01.Key words: genetic variability, cacauhy, inbreeding, Amazon, anthropic influence, microsatellite.The Amazon is an extraordinary supplier of natural resources to the Brazilian and world populations. The sustainable use of these resources and the lack of biological knowledge about most of the Amazonian flora species are challenges for future generations (Silva et al., 2015).Theobroma speciosum Willd. ex Spreng. (cacauhy) is native to the Amazonian region and it is distributed in primary forests of unflooded lands. This species, although little known, is important because it represents a possible source of resistance among most of the economically relevant species belonging to genus Theobroma (Silva et al., 2015).Native Theobroma species, such as cacauhy, are losing their habitat due to the intense forest fragmentation in the Amazon, and thus preserving the genetic diversity has been the main goal of most conservation programs focused on preserving the gene of interest and on allowing species variability maintenance at genetic level (Bekessy et al., 2002).Forest fragmentation decreases the number of individuals in a given population and, consequently, favors genetic variation losses. Genetic drift is the measured gene frequency of these individuals. In the short term, apart from the gene frequency of the original population, including the allele losses, genetic drift may occur in this small population. It is likely to have increased inbre...
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