999 resultados para 240992 Genética molecular de plantas
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Brazil is one of the major centers of diversity for polyploid cotton plants; these plants belong to the genus Gossypium, which has three known species: G. hirsutum, G. barbadense and G. mustelinum. The Northeast is the only region where the three species occur, the last group being endemic. Northeast s cotton plants can be important sources of variability for genetic breeding. It is believed that great part of local diversity is being lost, due to economic, political, cultural and agricultural problems. In an attempt to mitigate this loss and delineate conservation strategies it is necessary to know how the species are found where they occur. The objective was to characterize and determine how plants are maintained in situ in the states of Maranhão, Piauí, Ceará, Rio Grande do Norte and Paraíba at the beginning of the XXI century. The in situ characterization of G. hirsutum and G. barbadense was conducted through structured interviews with the cotton plants owners and through the analysis of the environment. The data were collected during expeditions undertaken between the years 2004 to 2005. Twenty-two plants were collected in the state of Paraíba, forty-four in the state of Rio Grande do Norte, one hundred and forty-six in the state of Ceará, forty in the state of Maranhão and ninety-one plants in the state of Piauí. All plants collected in the states of Paraíba and Rio Grande do Norte belonged to moco type. Moco cotton plants also predominated in the other states, representing 92%, 62% and 78% of plants collected in Ceará, Piauí and Maranhão, respectively. The other cotton plants collected belong to the species G. barbadense. The cotton plants were found in situ as dooryard plants, roads side, feral populations, cultivation or local varieties. Great part were dooryard plants (45.2%), being major in Piauí and Maranhão. Cultivation predominated in Ceará; in Rio Grande do Norte feral populations were the most frequent and, in Paraíba, local varieties. The maintenance of moco plants is related, mainly, to the phytotherapic domestic use (20.9%) and to confection of lamp wicks (29.7%). Few inhabitants in Paraíba, Rio Grande do Norte, Piauí and none in Maranhão used harvest the plants, storage the seeds or gin; however, in Ceará, 40.5% of owners affirmed that they harvested and commercialized the fiber. It was found that the maintenance of species is dependent of the fragile cultural habits of local inhabitants, therefore the maintenance in situ is not a suitable way to conservation of genetic resources. The efforts must be directed to the continuity of collections, maintenance and characterization ex situ
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Gossypium mustelinum Miers ex Watt is the only cotton species native from Brazil. It is endemic of the semi-arid region from North-east of the country, where it occur near from resilient water sources. The threats to the in situ conservation of the populations are caused by human interference in its habitat, mainly by excessive cattle graze and deforestation. Establish efficient strategies of in situ conservation depend on the accomplishment of a diagnosis of how the specie is found in its natural environment, and the knowledge about the genetic structure of the populations. The objectives of this work were i) to determine the in situ conditions of two populations present in rivers from basin of Rio Paraguaçu at the Bahia State, ii) to evaluate the structure and genetic variability presented in both populations, iii) to establish in situ and ex situ conservation strategies. It were realized collection in november 2007, when was realized in situ characterization of G. mustelinum. SSR markers were used for analyze 218 genotypes deriving from two populations of the G. mustelinum, localized at Tocó river and the Capivara river. The allelic frequencies, the heterozigosity and the F statics were estimated. All the plants were classified as wild and natives, and there was no evidence of the use the plants or its parts. The populations showed different conservation conditions in situ. Few plantlets were found in sites with excessive cattle feed, an indication that the damages in young plants should be high enough to compromise the renovation of the populations. On the other hand, populations were well preserved when the anthropic damages was low or inexistent. The 14 SSR primer pairs amplified 17 loci with a medium number of 5 alleles per locus (a total of 85 alleles). The high level of endogamy estimated (FIS=0,808) and the low observed heterozygosity (H0=0,093) were indicatives that the populations reproduce mainly by selfing, geitonogamy and crosses between related individuals. The genetic diversity was high (HE=0,482) and the differentiation between the populations was very high (FST=0,328). At least two sites from both populations of G. mustelinum must be preserved to achieve suitable in situ conservation. Actions that preserve the gallery forest and keep the cattle away should implemented, and could be as simple as erecting a fence. It is not possible anticipated if the in situ preservation will be possible. Therefore collections and ex situ preservation of representative specimens are essential to conserve the genetic diversity of native G. mustelinum
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Brazil has been considered one of the diversity centers of Gossypium barbadense species. It is believed that a relatively big erosion genetic process occurs with the species, due to economic, cultural and agricultural problems. A local diagnostic about species situation is the first step for reducing the diversity loss and establishing conservation strategies in situ. This research aimed the identification of the presence of Gossypium populations, characterization, determination of the main risks and collection of the accesses to store in germoplam banks, in Para and Amapa States. Expeditions were conducted in November 2004. An interview was carried out with the plant proprietor for characterizing in situ of G. barbadense species and of the environment where the plants were inserted. On hundred seventy nine plants in 22 municipal districts were collected in Para State and 117 plants in nine municipal districts in Amapa State. The majority of plants belong to G. barbadense species (98% in Amapa and 94% in Para). Plants occur in back yards, beside roads and spontaneously. That ones from back yards were more abundant (97% in Amapa and 95% in Para) and maintained as medicinal plants as the principal reason. Plants in natural environments in both states evaluated were not found, therefore, the creation of reserves and the application of others conventional methods of maintenance in situ are not applicable. The plant proprietors do not use to store or process seeds. Seed storage was reported as a practice by only 1% of the plant proprietors from Para and 11% from Amapa. The most plants collected were from two to three years of age (58% in Amapa and 93% in Para). As conclusions G. barbadense is the species most spread in the two studied states and are found in back yards. In Amapa State the botanical variety barbadense or Quebradinho is predominant, whereas in Para State the predominant variety is brasiliense or Rim-de-boi. Adequate conservation of thestudied species must be carried out in germoplasm collections maintained ex situ
Diversidade genética de populações naturais de pariparoba [Pothomorphe umbellata (L.) Miq.] por RAPD
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O objetivo desse trabalho foi analisar a estrutura genética de populações de Pothomorphe umbellata (L.) Miq. com base em polimorfismos moleculares do tipo RAPD. Foram analisadas quatro populações naturais do estado de São Paulo (Jacareí, Jundiaí, Piquete e Ubatuba) e uma população do Paraná (Adrianópolis). Foram identificados 25 locos polimórficos (96,15%). Elevados índices de diversidade genética foram observados dentro das populações (Hs = 0,2220). Verificou-se que 65,33% da variabilidade genética total encontra-se dentro das populações e 34,67% entre as populações; índices estes, obtidos a partir do cálculo da divergência genética (G ST = 0,3467). Os resultados sugerem que essas populações possuem níveis elevados de variabilidade genética, a qual pode ser fortemente impactada pela ação humana.
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Molecular markers have gradually replaced morphological markers in population studies. The advantages of molecular markers are the speed and precision of evaluations, mainly for long cycle cultures, where determinate traits can take years to manifest. The principle objectives of this research were to assess variability and genetic distances in four generations of Eucalyptus urophylla and provide data that help with the continued improvement of these materials. The populations can be found at the Experimental Forestry Sciences Station, Anhembi, SP, belonging to the College of Agriculture Luiz de Queiroz of São Paulo University. The initial base population was introduced by seeds collected in indonesia and designated P0 generation. The subsequent segregated generations, derivatives of recombination starting with open pollination, were designated P1, P2, and P3. One hundred and seventy four individual trees representing the four generations were analysed. The RAPD technique allowed the identification of 86 loci that were analysed with the Jaccard Coefficient, generating a genetic similarity matrix, permitting the estimation of genetic distances. The genetic distance of generation PO was 0.3338333, P1 was 0.336824, P2 was 0.40000, and P3 was 0.381093. In percentage terms the genetic distances between individuals grew in relation to base population, being 0.15% for generation P1, 18.93% for P2, and 13.31% for P3. This shows an increase in genetic variability with the advance of the program, despite the selective processes. From this came the belief that the initial base population was resulting from seed collection from isolated trees. These populations, although going through successive selections, had a high cross efficiency through satisfactory pollination, which then permitted genetic variation to increase, the outcome of effective recombination between individuals. Generations P2 and P3 gave a better perspective for the continuance of the improvement program due to the high number of different groups with standard genetic distances of 35%. The selections made between the diverse genetic groups allowed the efficient use of genetic variability evaluation.
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Molecular markers have recently been incorporated into genetic improvement programs. They are already considered as powerful tools with several different uses, for instance the monitoring of genetic variability in tree populations. The main objectives of this study were to evaluate genetic variability in Eucalyptus urophylla progenies and together with silvicultural and botanical information, provide assistance to the improvement program. The Eucalypts population is located at the Experimental Forestry Sciences Station, Anhembi, SP, which belongs to the College of Agriculture Luiz de Queiroz. Sixty-nine progenies were analysed representing one individual by family in open pollinated Eucalyptus urophylla trees. The RAPD technique allowed the identification of 72 loci that were analysed using Jaccard's Coefficient generating a genetic similarity matrix to permit estimation of genetic distances. The results obtained showed genetic distance between individuals of 0.40 with 12 groups of genetic variability using a standardised distance of 40%. The progenies showed different bark patterns, allowing the establishment of bark groups. The groups formed based on genetic distances obtained using DNA analysis did not correspond to those based on bark pattern. Genetic selection was simulated in which silvicultural and genetic variability data were linked, thus avoiding excessive variability losses. The simulation of controlled crossings allowed the maximum genetic difference to be obtained linked with height and individual bark roughness.
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The rambutan (Nephelium lappaceum) is an exotic fruit with great market potential in Brazil. However, there are few available informations about plants with potential for cultivation, because great morphologic variation is observed among plants and for consequence, little uniformity in the orchards and in the fruits. This research had for objective to evaluate the genetic diversity of a collection of rambutan plants obtained by seeds through morfo-chemical analyses of plants and fruits and by fAFLP molecular markers, to indication of promising materials to be used in new plantings of the culture in the São Paulo State. Was verified that both markers, morphologic and molecular, were efficient in the distinction of varieties, showing the presence of genetic variability among the plants of this study. Was also verified that the materials A51 and B03 presented a larger group of desirable characteristics for new cultivations of the fruitful.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Genética - IBILCE
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Pós-graduação em Agronomia (Genética e Melhoramento de Plantas) - FCAV
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)