Fitopatologia - Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11741
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Item Positioning of the major locus for Puccinia psidii rust resistance (Ppr1) on the Eucalyptus reference map and its validation across unrelated pedigrees(Tree Genetics & Genomes, 2010-06-12) Guimarães, Lucio M. S.; Mamani, Eva M. C.; Bueno, Nathalia W.; Faria, Danielle A.; Lau, Douglas; Alfenas, Acelino C.; Grattapaglia, DarioIn this report the major locus for Puccinia psidii rust resistance, Ppr1, was positioned on the reference genetic map for Eucalyptus. Additionally, its position was validated by association genetics in a related and two unrelated pedigrees involving different Eucalyptus grandis resistant trees crossed to individuals of two other species, Eucalyptus tereticornis and Eucalyptus camaldulensis. These results are consistent with the hypothesis that Ppr1 controls a large proportion of the variation for rust resistance, strengthening its role as a major locus in Eucalyptus and providing its unequivocal genomic position on linkage group 3. A localized map with 19 microsatellite loci was built around Ppr1. Multiallelic profiles were observed at several mapped microsatellites suggesting recent tandem duplications in the genomic landscape surrounding Ppr1. Markers EMBRA125 and EMBRA1071 flank Ppr1 at 9.5% and 7% recombination, respectively, and were found to be in linkage equilibrium in a E. grandis breeding population, consistent with the expectations in outcrossed Eucalyptus. Their potential use for MAS will specifically be directed to identifying resistant offspring of P. psidii resistant parent trees that are heterozygous at Ppr1. In these circumstances, a significant amount of LD is expected to occur between specific alleles at flanking microsatellites and the resistance allele at Ppr1. Moreover, the positional information of Ppr1 paves the way for prospective undertakings in this genomic region with the upcoming availability of a draft genome for E. grandis.Item Genetic diversity and interfertility among highly differentiated populations of Ceratocystis fimbriata in Brazil(Plant Pathology, 2010-07-01) Ferreira, E. M.; Harrington, T. C.; Thorpe, D. J.; Alfenas, A. C.Mating studies showed that isolates of the insect-associated wilt pathogen Ceratocystis fimbriata from Eucalyptus spp., mango, fig, inhame (Colocasia esculenta), Gmelina arborea and sweet potato were interfertile, and progeny from those crosses showed normal segregation for microsatellite markers. Genetic diversity was compared among 13 populations of C. fimbriata collected from six states in Brazil using 15 highly polymorphic microsatellite markers. The gene diversity values of most eucalyptus and mango populations from Minas Gerais, Bahia, Rio de Janeiro and São Paulo states were similar to putatively native populations of Ceratocystis platani and C. cacaofunesta, two other species in the C. fimbriata complex that are homothallic. Index of association values indicated substantial asexual reproduction or selfing in populations on mango and eucalyptus. Most of these eucalyptus and mango populations were not highly differentiated from each other, and these populations and genotypes appeared to be more closely related to each other than to other populations by UPGMA analyses. By contrast, the G. arborea population from Pará and the fig and inhame populations from São Paulo had relatively low lev- els of diversity and were highly differentiated from each other and all other studied populations, suggesting that they were from different origins and had gone through genetic bottlenecks. One of the eucalyptus populations in Bahia consisted of a single genotype and may have been introduced to the site in infected cuttings from another Bahia location. Similarly, a mango population from Mato Grosso do Sul consisted of a single genotype, which was identical to one of the genotypes found on mango in São Paulo. Aside from introductions by humans, mating studies and genetic analyses suggest that limited dispersal distance and a high degree of selfing or asexual reproduction lead to local populations of C. fimbriata that have limited diversity but are highly differentiated from other populations.Item Cloning and characterization of gene-resistant analogs (RGAs) involved in rust (Puccinia psidii) resistance in Eucalyptus grandis(Journal of Forestry Research, 2015-09) Alfenas, Acelino Couto; Laia, Marcelo Luiz; Brommonschenkel, Sergio Hermínio; Oda, Shinitiro; Melo, Eduardo José de; Silva, Inaê Mariê de Araújo; Gonçalves, Janaína Fernandes; Marques, AriadneDisease-resistant genes play an important role in defending against a variety of pathogens and insect pests in plants. Most of the disease-resistant genes encode proteins with conserved leucine rich repeat and nucleotide binding site domains. In this study, we cloned and characterized gene-resistant analogs (RGAs) from Eucalyptus grandis using degenerate PCR, with primers specifically targeting these two domains. The amplified fragments were cloned into the pGEM-T vector and transformed into Escherichia coli. Among the 90 clones obtained, 13 were sequenced and compared with each other and with previously identified gene-resistant diseases. A BLASTX search in GenBank revealed high similarities among the conserved domains of these cloned genes with RGA genes. Some clones, however, showed no significant similarity with DNA sequences in GenBank. Southern blotting analysis identified several polymorphic RFLP loci between distinct genotypes. However, none of them co-segregated with the Puccinia psidii Winter resistance gene 1 (Ppr1) in a population study.Item Método de seleção e identificação de fontes de resistência à murcha do eucalipto causada por Ceratocystis fimbriata(Revista Árvore, 2011-04-20) Alfenas, Acelino Couto; Mafia, Reginaldo Gonçalves; Ferreira, Eraclides Maria; Binoti, Daniel Henrique BredaEste trabalho teve como objetivo desenvolver um método de seleção e identificar fontes de resistência à murcha do eucalipto causada por Ceratocystis fimbriata. A inoculação de 5 ml de inóculo (2,5 x 10^4 esporos/ml) do patógeno em um ferimento no coleto de mudas com 60 dias de idade foi o método mais eficiente na reprodução dos sintomas da doença. Para este método, a severidade da doença e a mortalidade de plantas em função do tempo após a inoculação foram avaliadas. Um período de 30 dias após a inoculação foi suficiente para reproduzir os sintomas da doença. O protocolo de inoculação desenvolvido apresentou alto rendimento (400 plantas/ h) e menor consumo de espaço, quando comparado com outros métodos, principalmente pelo fato de possibilitar a inoculação de mudas jovens de eucalipto, entre 60 e 90 dias. Na segunda etapa do trabalho, a resistência interespecífica do eucalipto a C. fimbriata foi avaliada usando as espécies Eucalyptus camaldulensis, E. dunnii, E. grandis, E. pellita, E. saligna, E. tereticornis e E. urophylla. Houve segregação da resistência para todas as espécies e de acordo com o local de origem da população. Para E. urophylla, por exemplo, ocorreram as maiores variações entre o número de indivíduos resistentes e suscetíveis à doença. Essas variações podem estar ligadas com a procedência das sementes e com as características do programa de melhoramento genético.