Isoenzimas de Eucalyptus: técnicas para extracao e eletroforese.

Visou-se, com este estudo, determinar os metodos mais adequados para a extracao e a separacao eletroforetica de isoenzimas de E. . Examinaram-se zimogramas em gel de amido, obtidos a partir de extrato de folhas,de polen, de plantulas mantidas por micropropagacao e de plantulas obtidas de sementes. Testaram-se quatro metodos mecanicos para a maceracao dos tecidos vegetais, cinco sistemas-tampao para a extracao das enzimas e 16 combinacoes de sistemas-tampao gel/eletrodo para a eletroforese. Sao apresentados e discutidos os resultados obtidos com o uso desses sistemas-tampao para a identificacao de 34 enzimas nos quatro materiais mencionados. Este trabalho fornece uma escolha de marcadores isoenzimaticos aplicaveis ao melhoramento de Eucalyptus.Edição dos Anais do Congresso Florestal Brasileiro, 6., 1990, Campos do Jordão

Genetic basis of resistance in Eucalyptus spp. pathosystems.

Coordenadores técnicos: Richard A. Sniezko, Alvin D. Yanchuk, John T. Kliejunas, Katharine M. Palmieri, Janice M. Alexander, Susan J. Frankel

Efeito "in vitro" de antibióticos e rizobactérias no controle de bactérias fitopatogênicas ao Eucalyptus spp.

Doenças causadas por bactérias constituem um novo desafio à cultura do Eucalyptus spp., podendo, inclusive, limitar o uso de clones suscetíveis. O presente trabalho objetivou avaliar a eficiência de antibióticos e rizobactérias na inibição do crescimento "in vitro" de isolados de bactérias fitopatogênicas ao Eucalyptus spp. na fase de viveiro e de campo. O antibiótico sulfato de amicacina e a rizobactéria S1 (Bacillus subtillis) destacaram-se quanto à inibição do crescimento do isolado fitopatogênico IP1-05 (Pseudomonas chichorii), enquanto a cefoxitina causou maior inibição dos isolados BSV16 e RVV11 (Rhizobium sp.). Os antibióticos de uso comercial na área agronômica, Mycoshield (oxitetraciclina) e Agrimicina (estreptomicina e tetraciclina) foram pouco efetivos. Este trabalho proporciona embasamento a alternativas para controle biológico de doenças bacterianas em mudas de Eucalyptus spp. na fase de viveiro

Etiology of bacterial leaf blight of eucalyptus in Brazil.

Bacterial leaf blight of eucalyptus is initially characterized by water soaked, angular, amphigenous and interveinal lesions, concentrated along the main vein, at the edges or scattered on the leaf blade. As the disease progresses, the lesions become brown to pale, and when young leaves are infected leaf cut areas at the edges or perforations at the center of the lesions may appear due to abortion of the necrotic area. Eventually, necrosis may be found on petiole and twigs. Leaf fall commonly occurs on highly susceptible genotypes due to the early senescence of diseased leaves. Precise diagnosis is accomplished by bacterial exudation from leaf sections placed in a water drop under light microscope (200 x). Twenty-five bacterial isolates from Amapá (2), Bahia (4), Minas Gerais (2), São Paulo (9), Pará (3), Mato Grosso do Sul (1), and Rio Grande do Sul (4) States, which induced hypersensitive reaction (HR) in non-host plants and were pathogenic to eucalyptus, when inoculated by inoculum injection, were identified by biochemical assays, using carbon sources (MicroLogTM BIOLOG) and sequence analysis (16S rDNA). Ten isolates were identified as Xanthomonas axonopodis, four as X. campestris, four as Pseudomonas syringae, two as P. putida, two as P. cichorii, one as Erwinia sp., and two were similar to bacterial genera of Rhizobiaceae. When spray inoculated on intact plants of eucalyptus, only X. axonopodis, P. cichorii and isolates of the Rhizobiaceae family induced typical symptoms of the disease and were considered pathogenic. In Brazil, X. axonopodis seems to be the most widespread species causing the bacterial leaf blight of Eucalyptus spp

Resistance of Eucalyptus pellita to rust (Puccinia psidii).

Eucalypts 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

Análise de ligação entre marcadores dominantes e co-dominantes em famílias de irmãos completos de espécies alógamas.

Tendo em vista que ferramentas genômicas como microarranjos de DNA têm levado ao desenvolvimento de novos procedimentos de genotipagem, é provável que no futuro mapas de alta densidade sejam construídos a partir de marcadores dominantes e co-dominantes. Recentemente, uma abordagem estritamente genética foi descrita para a estimação da freqüência de recombinação (r) entre marcadores moleculares em famílias de irmãos completos de espécies alógamas. Entretanto, uma configuração em particular envolvendo marcadores dominantes que segregam na razão de 3:1, e marcadores co-dominantes não foi considerada. Neste trabalho, nove estimadores para cálculo de r entre marcadores dominantes e co-dominantes são apresentados, de modo que todas as combinações entre marcadores moleculares (dois a quatro alelos), incluindo segregação em um ou ambos os genitores, dominância e todas as fases de ligação em famílias de irmãos completos são contempladas

Suppression of Botrytis cinerea sporulation by Clonostachys rosea on rose debris: a valuable component in Botrytis blight management in commercial greenhouses.

Botrytis blight, caused by Botrytis cinerea (Bc), is an important disease on roses grown in plastic greenhouses in Brazil. Biocontrol with Clonostachys rosea (Cr) applied to leaves and crop debris to reduce pathogen sporulation can complement other control measures for disease management. Two experiments, each with a rose cultivar, were conducted in a plastic greenhouse. For ?Red Success,? four treatments were compared: (1) control; (2) fortnightly sprays of Cr; (3) weekly sprays of mancozeb; and (4) weekly sprays of either Cr or mancozeb to the lower third of the plants and the debris. For ?Sonia,? treatment 4 was not included. Samples were taken from debris (leaves and petals) at ten 15-day intervals and plated on PCA medium. Sporulation of fungi and incidence of Botrytis blight on buds were assessed. For both cultivars, C treatments significantly (P=0.05) reduced Bc sporulation. However, disease incidence was not consistently reduced, probably because the applications of C. rosea started when Botrytis blight epidemic was advanced and no sanitation practices were performed on nontreated plots. From the present and previous studies, continuous application of Cr on debris, associated with sanitation practices, has the potential to reduce Bc sporulation and disease incidence in the buds