Diversidade genética, sistema de reprodução e parentesco em progênies de Eucalyptus urophylla S.T. Blake
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Data
2018-02-02
Autores
Pupin, Silvelise
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Universidade Estadual Paulista (Unesp)
Resumo
O êxito dos programas de melhoramento florestal requer que a predição do progresso genético seja proporcional ao progresso genético real. Para isso, é possível unir a genética quantitativa com ferramentas moleculares, que permitem estimar parâmetros com maior acuidade para seleção. O objetivo foi verificar a diversidade genética, o sistema de reprodução e as relações de parentesco em populações de polinização aberta de Eucalyptus urophylla, para selecionar cruzamentos e genitores. Para tanto, foram utilizados dois Pomares de Sementes por Mudas (PSM) e uma amostra de indivíduos adultos em um teste de progênies (PCPN). Para compor um teste de progênies de segunda geração (TP2G) foram coletadas sementes em 23 árvores matrizes em um dos PSM. As populações estão localizadas na Fazenda de Ensino, Pesquisa e Extensão, em Selvíria-MS. Os indivíduos do TP2G (722) e os adultos (467) foram genotipados com 12 marcadores microssatélites (SSR) e os locos avaliados para verificar se são marcadores genéticos. Os caracteres silviculturais foram mensurados nos PSM e no TP2G. Os marcadores SSR formaram um conjunto consistente de marcadores genéticos. A diversidade genética das populações foi elevada e a redução foi pequena entre as gerações. O índice de fixação foi significativo para todas as populações e maior nos descendentes, a indicar a presença de endogamia. A taxa de cruzamento indicou que a reprodução ocorreu predominantemente por cruzamentos (0,964). Houve cruzamentos entre parentes, correlacionados e autofecundação. Em função disso, a endogamia nas progênies foi superior a população parental e a principal razão foi o cruzamento entre parentes, o que resultou em maior endogamia. Além disso, as relações de parentesco foram superiores no TP2G. Houve fluxo de pólen entre as populações e o número de doadores de pólen foi elevado pela análise de paternidade, que permitiu determinar o provável candidato a pai de 713 indivíduos do TP2G. Com isso foi possível estudar o teste de progênies de polinização aberta como um teste de irmãos completos, permitindo estimar as capacidades gerais e específicas de combinação. Para o diâmetro a altura do peito o ganho genético baseado no valor genotípico do cruzamento foi elevado (> 20%), assim como a seleção clonal, que indicou ganhos consideráveis (> 65%). Assim, é possível dar continuidade ao Programa de Melhoramento, indicando cruzamentos e genótipos promissores de E. urophylla.
The success of forest breeding programs requires that the prediction of genetic progress be proportionate to actual genetic progress. For this, it is possible to join the quantitative genetics with molecular tools, which allow to estimate parameters with greater acuity for selection. The main was to verify the genetic diversity, mating system and kinship relationships in open pollinated populations of Eucalyptus urophylla, to select crosses and parents. In order to do, two seedlings seed orchards (SSO) and an adult sample of individuals were used in a progeny test (PCPN). To compose a second generation progenies test (2GPT) seeds were collected in 23 mother trees in one of the SSO. The populations are located in the Fazenda de Ensino, Pesquisa e Extensão, in Selvíria-MS. The individuals from 2GTP (722) and adults (467) were genotyped with 12 microsatellite markers (SSR) and the loci evaluated for genetic markers. Silvicultural traits were measured in the SSO and 2GPT. SSR markers formed a consistent set of genetic markers. The genetic diversity of the populations was high and the reduction was small between generations. The fixation index was significant for all populations and higher in the offspring, indicating the presence of inbreeding. The multilocus estimate of outcrossing rate indicated that reproduction occurred predominantly by crosses (0.964). There were crosses between relatives, crosses correlated and self-fertilization. As a result, inbreeding in the progenies was higher than in the parental population and the main reason was cross between relatives. In addition, kinship relations were higher in 2GPT. There was pollen flow among the populations and the number of pollen donors was higher by paternity analysis, which allowed to determine the probable candidate father of 713 individuals of the 2GPT. Thus, it was possible to study the open pollinated progeny test as a full sib test, allowing the estimation of general and specific combining abilities. For the diameter at breast height, the genetic gain based on the genotypic value of the cross was high (> 20%), as well as the clonal selection, which indicated considerable gains (> 65%). Thus, it is possible to continue the Breeding Program, indicating promising crosses and genotypes of E. urophylla.
The success of forest breeding programs requires that the prediction of genetic progress be proportionate to actual genetic progress. For this, it is possible to join the quantitative genetics with molecular tools, which allow to estimate parameters with greater acuity for selection. The main was to verify the genetic diversity, mating system and kinship relationships in open pollinated populations of Eucalyptus urophylla, to select crosses and parents. In order to do, two seedlings seed orchards (SSO) and an adult sample of individuals were used in a progeny test (PCPN). To compose a second generation progenies test (2GPT) seeds were collected in 23 mother trees in one of the SSO. The populations are located in the Fazenda de Ensino, Pesquisa e Extensão, in Selvíria-MS. The individuals from 2GTP (722) and adults (467) were genotyped with 12 microsatellite markers (SSR) and the loci evaluated for genetic markers. Silvicultural traits were measured in the SSO and 2GPT. SSR markers formed a consistent set of genetic markers. The genetic diversity of the populations was high and the reduction was small between generations. The fixation index was significant for all populations and higher in the offspring, indicating the presence of inbreeding. The multilocus estimate of outcrossing rate indicated that reproduction occurred predominantly by crosses (0.964). There were crosses between relatives, crosses correlated and self-fertilization. As a result, inbreeding in the progenies was higher than in the parental population and the main reason was cross between relatives. In addition, kinship relations were higher in 2GPT. There was pollen flow among the populations and the number of pollen donors was higher by paternity analysis, which allowed to determine the probable candidate father of 713 individuals of the 2GPT. Thus, it was possible to study the open pollinated progeny test as a full sib test, allowing the estimation of general and specific combining abilities. For the diameter at breast height, the genetic gain based on the genotypic value of the cross was high (> 20%), as well as the clonal selection, which indicated considerable gains (> 65%). Thus, it is possible to continue the Breeding Program, indicating promising crosses and genotypes of E. urophylla.
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Palavras-chave
Coancestria, Endogamia, Microssatélites, Pomar de sementes por mudas, Teste de progênies de segunda geração, Inbreeding, Kinship, Microsatellite, Seedling seed orchard, Second generation progeny test