Fitopatologia - Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11741
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Item Genetic mapping and validation of QTLs associated with resistance to Calonectria leaf blight caused by Calonectria pteridis in Eucalyptus(Tree Genetics & Genomes, 2014-11-15) Zarpelon, Talyta Gafassi; Guimarães, Lúcio Mauro da Silva; Faria, Danielle Assis; Coutinho, Marcelo Magalhães; Cápua Neto, Braz; Teixeira, Ramon Ubirajara; Grattapaglia, Dario; Alfenas, Acelino CoutoCalonectria leaf blight (CLB) caused by Calonectria pteridis is one of the main leaf diseases in Brazilian Eucalyptus plantations in warm climates with prolonged periods of rain. The main symptoms are leaf spots followed by intense defoliation in highly susceptible plants. Exploiting the existing inter- and intraspecific variability for defoliation is the best option to control this disease. Nevertheless, nothing is known about the genetic architecture of resistance to CLB in Eucalyptus. We built microsatellite-based genetic maps for E. urophylla × E. camaldulensis (EU11 × EC06) F1 family of 89 plants. Four or five clonal replicates per individual offspring were clonally propagated, totalling 445 plants which were phenotyped for defoliation in the basal third of the branches at 30 days following controlled inoculation with a single-spore isolate. Genetic mapping was performed using a pseudo-testcross, and QTLs detected using composite interval mapping. Five QTLs were detected for resistance to CLB; of them, only one could be validated in two unrelated pedigrees, and its effect was conservatively estimated as controlling between 5 and 10 % of the phenotypic variation when the bias derived from the limited size of the mapping population was taken into account. This work provides a starting point for future studies of the genetics of resistance to CLB, and adds further evidence to the challenge of ascertaining the effects of QTLs detected in a single biparental background across unrelated families.Item Resistance of Eucalyptus pellita to rust (Puccinia psidii)(Crop Breeding and Applied Biotechnology, 2014-09-15) Santos, Marisângela Rodrigues; Guimarães, Lúcio Mauro da Silva; Resende, Marcos Deon Vilela de; Rosse, Leonardo Novaes; Zamprogno, Karina Carnielli; Alfenas, Acelino CoutoEucalypts rust (Puccinia psidii) is currently one of the major diseases in commercial eucalypt plantations in Brazil. The primary method of disease control is the use of resistant genotypes, and, among the different species of Eucalyptus, E. pellita is indicated as a promising source of resistance. In this work, the genetic control of rust resistance in E. pellita through inoculations under controlled conditions of 441 plants from four full-sibling families was studied. Inoculations were performed using the monopostular isolate UFV-2, race 1. All families tested segregated for rust resistance, and the number of resistant plants was higher than susceptible in all crosses. Inheritance models based on few genes did not fully explain the observed segregation patterns, and the narrow-sense heritability of rust resistance was estimated between 32.7% and 37.3%. The results suggested that rust resistance in E. pellita is complex and is controlled by major- and minor-effect genes.Item Genetic control of Eucalyptus urophylla and E. grandis resistance to canker caused by Chrysoporthe cubensis(Genetics and Molecular Biology, 2010-09-01) Guimarães, Lúcio Mauro da Silva; Resende, Marcos Deon Vilela de; Lau, Douglas; Rosse, Leonardo Novaes; Alves, Alexandre Alonso; Alfenas, Acelino CoutoChrysophorte cubensis induced canker occurs in nearly all tropical and subtropical regions where eucalypts are planted, causing losses in both wood quality and volume productivity, especially so in the warmer and more humid regions of Brazil. The wide inter and intra-specific genetic variability of resistance to canker among Eucalyptus species facilitates the selection of resistant plants. In this study, we evaluated resistance to this pathogen in five Eucalyptus grandis (G) and 15 E. urophylla (U) trees, as well as in 495 individuals from 27 progenies derived from crosses between the trees. In the field, six-months-old test seedlings were inoculated with C. cubensis. Lesion length in the xylem and bark was measured eight months later. The results demonstrated that xylem lesions could preferentially be used for the selection of resistant clones. Eight trees (7 U and 1 G) were susceptible, and the remainder (8 U and 4 G) resistant. Individual narrow and broad sense heritability estimates were 17 and 81%, respectively, thereby suggesting that canker resistance is quantitative and highly dependent on dominance and epistasis.