Few reports are available about the ichthyofauna of typical semi-arid rivers, although the regional diversity has been constantly threatened by human activities, mainly related to impoundment and construction of dams. The goal of the present work was to evaluate using different methods, the population genetic structure of a characin fish, Astyanax aff. bimaculatus, widespread throughout hydrographic basins of Bahia, Northeastern Brazil. Morphological (meristic and morphometric data), cytogenetic (karyotype and Ag-NOR), and molecular (RAPD and SPAR) analyses were carried out in specimens collected upstream and downstream of Pedra Dam, in the main channel of Contas River (Contas River Basin), and in the Mineiro stream, which belongs to the adjacent Recôncavo Sul basin. Few external differences were detected among populations, where the individuals collected upstream of Pedra Dam were slightly larger than the others. Cytogenetic data also showed a similar karyotypic pattern (2n=50; 6m+28sm+12st+4a; FN= 96) and NORs located on the short arms of up to two chromosome pairs, with numerical inter- and intra-populational variation. Nonetheless, RAPD and SPAR analyses differentiated reliably the three populations, revealing striking differences in the allele frequencies among the localities studied and a significant difference in population structure index (Fst=0.1868, P<0.0001). The differences between populations within a same river were as significant as those between distinct hydrographic basins, indicating that the dam/reservoir represents an effective barrier to gene flow. Additionally, environmental peculiarities from each locality are also believed to influence the genetic patterns detected herein. On the other hand, the similarity between samples from Contas River and Recôncavo Sul basins could be related to a common evolutionary history, since both basins are geographically close to each other. Finally, the present study shows that a multi-approach analysis is particularly useful in identifying the population structure of widely distributed species and to evaluate the impacts of human activities on natural fish populations.
Poucos estudos ictiofaunísticos estão disponíveis em rios típicos do semi-árido, apesar da constante ameaça à diversidade local devido a influências antrópicas, com destaque para o represamento e construção de barragens. O presente trabalho teve como objetivo avaliar, por meio de diferentes metodologias, a estrutura genética de populações de uma espécie de caracídeo, Astyanax aff. bimaculatus, amplamente distribuída em bacias hidrográficas da Bahia, Nordeste do Brasil. Análises morfológicas (dados merísticos e morfométricos), citogenéticas (cariótipo e Ag-RONs) e moleculares (RAPD e SPAR) foram realizadas em espécimes coletados à montante e à jusante da Barragem da Pedra, na calha principal do médio rio de Contas (bacia do Rio de Contas) e no ribeirão Mineiro, pertencente à bacia adjacente do Recôncavo Sul. Poucas diferenças externas foram detectadas entre as populações, sendo os indivíduos...

-(Population genetic structure of Copaifera langsdorffii Desf. (Leguminosae -Caesalpinioideae) in forest fragments in "Pontal do Paranapanema", SP, Brazil). The "Pontal do Paranapanema" is the most recently deforested region of the state of São Paulo in Brazil. The effects of forest fragmentation on the population genetic structure of Copaifera langsdorffii Desf. were evaluated by genotyping with six microsatellite loci at least 30 adult and 30 sapling individuals of three populations in "Pontal do Paranapanema". The sampling areas comprised two fragments located in the rural settlements Tucano (800 ha) and Madre Cristina (300 ha); and one population located in a continuous forest, the "Parque Estadual do Morro do Diabo" (35,000 ha). High levels of genetic diversity were detected in saplings and adults, gene diversity (H e ) ranged from 0.718 to 0.835 and average number of alleles per locus (Â) ranged from 8.67 to 11.83, showing that the fragmentation has not caused loss of alleles yet. The high estimated fixation indexes (from 0.183 to 0.387) are due to null alleles in some loci and the occurrence of inbreeding within populations. Genetic divergence was low among adults (R ST = 0.035) but increased among saplings (R ST = 0.075). As expected, forest fragmentation has caused a decrease in gene flow among the populations, especially between the most distant fragment (Tucano -about 8 km from the "Parque Estadual do Morro do Diabo"). An alternative to promote gene flow among forest fragments of "Pontal do Paranapanema" would be the settle of agroforests, which would act as stepping-stones, favouring pollen and seed dispersion among fragments.Key words -Atlantic forest, forest fragmentation, gene flow, genetic diversity, microsatellites RESUMO -(Estrutura genética populacional de Copaifera langsdorffii Desf. (Leguminosae -Caesalpinioideae) em fragmentos florestais no Pontal do Paranapanema, SP, Brasil) O Pontal do Paranapanema é a região mais recentemente desflorestada do Estado de São Paulo. Os efeitos da fragmentação florestal na estrutura genética de Copaifera langsdorffii Desf. foram avaliados por meio da genotipagem, com seis locos microssatélites, de pelo menos 30 indivíduos regenerantes e 30 adultos em três áreas do Pontal do Paranapanema. A amostragem compreendeu dois fragmentos localizados em assentamentos rurais, Tucano (800 ha) e Madre Cristina (300 ha); e uma população localizada em floresta contínua, no Parque Estadual do Morro do Diabo (35.000 ha). Níveis elevados de diversidade genética foram detectados tanto nos regenerantes como nos adultos. A diversidade gênica (H e ) variou de 0,718 a 0,835 e o número médio de alelos por loco (Â) variou de 8,67 a 11,83, mostrando que a fragmentação ainda não causou perda de alelos. As estimativas elevadas dos índices de fixação (0,183 a 0,387) foram conseqüentes da ocorrência de alelos nulos em alguns locos e de endogamia nas populações. A divergência genética foi pequena entre os adultos (R ST = 0,035), mas aumentou entre os regenerantes (R ST = 0,075). C...

The present study was conducted in five Gossypium mustelinum populations that were phenotyped and genotyped to quantify their resistance to the major diseases that affect cultivated cotton (G. hirsutum) in Brazil. Four G. mustelinum populations, in addition to genotypes of G. hirsutum and G. barbadense (resistant or susceptible controls), were phenotyped for resistance to cotton blue disease, angular leaf spot, common mosaic and ramulose. Artificial inoculation of cotton plants with causative agents of cotton blue disease, angular leaf spot and ramulose, as well as those naturally infested with common mosaic virus, showed that all G. mustelinum accessions were susceptible to every disease studied. Four microsatellite markers linked to disease resistance genes for cotton blue disease, angular leaf spot and root-knot nematodes (Meloidogyne spp.) in G. hirsutum were used for genotyping of the five populations. The markers amplified different alleles from those associated with resistance genes in cultivated cotton, revealing polymorphisms different from reported cases of G. hirsutum resistance. The susceptibility to all diseases studied may represent a phytosanitary risk for the in situ conservation of natural G. mustelinum populations.

The differentiation of closely related Citrus genotypes is a meticulous, laborious, and time-consuming task that involves the assessment of complex traits such as growth, tolerance to stress, photosynthetic efficiency, yield, and many others. Such a task is generally accomplished either by analyzing specific features of adult plants or by applying molecular markers to young trees. On one hand, only after plants start yielding can distinct genotypes be differentiated by comparing their fruit sizes, shapes, taste, and the number of seeds. On the other hand, molecular markers are expensive, and demand expertise and time for the analysis of a larger number of plants. For these reasons, the development of techniques that could assist in an early, quick and accurate differentiation of closely related Citrus varieties is of utmost importance. In this context, laser-induced fluorescence spectroscopy (LIFS) is a promising technique, since it is rapid, highly sensitive, and inexpensive. Previous studies showed that LIFS can differentiate a variety of sweet orange. However, this new study aimed to determine LIFS accuracy in the differentiation and grouping of very closely varieties of four Sunki mandarin selections: Comum, Florida, Tropical, and Maravilha. Furthermore we compared the results with ISSR and SSR molecular markers for the same varieties. LIFS technique distinguished the four selections with accuracy greater than 70%. Only with molecular markers was possible distinguishing clearly Tropical from Maravilha, but not Comum from Florida selections. In this way the results suggest that LIFS may be a sound tool for helping the identification of closely Citrus varieties.

ResumoTransferibilidade de primers heterólogos e acesso ao polimorismo de loci microssatélites em maracujazeiro-do-sono (Passilora setacea DC). Pares de primers que acessam loci microssatélites, inicialmente construídos a partir do genoma de Passilora edulis Sims lavicarpa e P. alata, foram testados quanto à sua capacidade de acessar loci microssatélites em indivíduos de maracujazeiro-do-sono (P. setacea). Sete dos trinta e um pares de primers testados foram capazes de acessar polimorismo de DNA no genoma dessa espécie silvestre de Passilora, ao avaliar seis populações naturais, localizadas em área de transição entre os biomas Caatinga e Cerrado, no estado da Bahia. O número de alelos/loci foi baixo, oscilando de um a quatro. A heterozigosidade média observada por locus em todas as populações variou de 0,13 a 0,40. Houve transferência dos pares de primers microssatélites heterólogos do gênero Passilora para maracujazeiro-do-sono, constituindo um novo conjunto de primers que acessam locus codominante aleatório nessa espécie, útil para ins de conservação e pré-melhoramento do maracujazeiro-do-sono. Palavras-chave: Diversidade genética; Maracujazeiro-do-sono; Simple sequence repeat; Transferibilidade AbstractPrimer pairs that access microsatellite loci, initially constructed through the genome of Passilora edulis Sims lavicarpa and P. alata, were tested concerning their ability to access microsatellite loci in "somnus" passion fruit tree (P. setacea) individuals. Seven out of the thirty one primer pairs tested were able to access DNA polymorphism in the genome of this wild Passilora species, by evaluating six natural populations, located in a transition area between the biomes Caatinga and Cerrado, in the state of Bahia, Brazil. The number of alleles/ loci was small, oscillating from 1 to 4. The average heterozygosity observed per locus in all populations ranged from 0.13 to 0.40. There was transference of heterologous microsatellite primer pairs from the Passilora genus to "somnus" passion fruit tree, constituting a new set of primers that access random co-dominant locus in this species, useful for conservationist purposes and pre-improvement of "somnus" passion fruit tree.