CHARACTERIZATION of RALSTONIA SOLANACEARUM STRAINS FROM BRAZIL USING MOLECULAR METHODS and PATHOGENICITY TESTS

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Atividade antibacteriana de óleos essenciais e extratos vegetais sobre o desenvolvimento de Ralstonia Solanacearum em mudas de bananeira

O presente trabalho teve como objetivo determinar a atividade de diferentes concentrações de óleos essenciais e extratos vegetais sobre o crescimento de Ralstonia solanacearum e a incidência do moko em mudas de bananeira. Foram avaliadas diferentes concentrações de óleos essenciais de citronela, eucalipto citriodora, cravo-da-índia e gengibre: 1,25%; 3,5%; 3,75% e 5% e de extratos de cravo-da-índia, gengibre, canela e melão-de-são-caetano: 5%, 10%, 15% e 20%, medindo-se o halo de inibição da bactéria, após 48 horas. O óleo de eucalipto e os extratos de melão-de-são-caetano, cravo-da-índia e canela não apresentaram efeito sobre a bactéria. O extrato de gengibre, os óleos de citronela, de cravo e de gengibre inibiram o crescimento de R. solanacearumem todas as concentrações testadas, destacando-se o óleo de cravo como o melhor tratamento, seguido por extrato de gengibre. Mudas de bananeira foram pulverizadas com os óleos de citronela, gengibre e cravo (3,75%) e extrato de gengibre (20%), aplicando-se 10 ml da solução por planta. Oito dias após, as mudas foram inoculadas com o patógeno (10(8) cel/mL). O óleo de citronela proporcionou o melhor resultado, com 100% de controle da doença, porém as folhas das plantas, com esse tratamento, apresentaram sintomas de fitotoxidez. O óleo e o extrato de gengibre foram semelhantes na eficiência de controle do moko (50%), e o óleo de cravo apresentou menor eficiência (25%).

Avaliação da agressividade e caracterização genética de linhagens de Ralstonia Solanacearum isoladas de diferentes plantas hospedeiras

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Resíduos da indústria pesqueira na indução de supressividade a Cylindrocladium spathiphylli e Ralstonia solanacearum e de biofertilizantes no controle de oídios

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Bottled mineral water as a potential source of antibiotic resistant bacteria

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Comparative genomic analysis of plant-associated bacteria

This review deals with a comparative analysis of seven genome sequences from plant-associated bacteria. These are the genomes of Agrobacterium tumefaciens, Mesorhizobium loti, Sinorhizobium meliloti, Xanthomonas campestris pv campestris, Xanthomonas axonopodis pv citri, Xylella fastidiosa, and Ralstonia solanacearum. Genome structure and the metabolism pathways available highlight the compromise between the genome size and lifestyle. Despite the recognized importance of the type III secretion system in controlling host compatibility, its presence is not universal in all necrogenic pathogens. Hemolysins, hemagglutinins, and some adhesins, previously reported only for mammalian pathogens, are present in most organisms discussed. Different numbers and combinations of cell wall degrading enzymes and genes to overcome the oxidative burst generally induced by the plant host are characterized in these genomes. A total of 19 genes not involved in housekeeping functions were found common to all these bacteria.

INCORPORATION of NEEM LEAVES INTO SOIL TO CONTROL BACTERIAL WILT of TOMATO

The objective of this study was to evaluate the effect of incorporation of neem (Azadirachta indica) leaves into the soil for controlling bacterial wilt of tomato caused by Ralstonia solanacearum. The experiment was conducted in a greenhouse of the State University of Maranhao (Brazil). Dry and fresh neem leaves were incorporated in the soil in different amounts (0, 20, 40, 60, 80 and 100 g) and kept in it for different periods of time (0, 15, 30, 45 and 60 days). After each of these periods, seedlings inoculated with R. solanacearum were transplanted in the amended soil. Results showed positive effects in the disease control by incorporating neem leaves, with a reduction of wilting symptoms up to 100% with dry leaves and 78% with fresh leaves.

Evaluation of antimicrobial activity of extracts of medicinal plants on three tomato phytopathogens

Antimicrobial activity of 45 extracts of medicinal plants were tested on Xanthomonas campestris pv. vesicatoria, Ralstonia solanacearum and Clavibacter michiganense subsp. michiganense. Some assays were done to verify the capability of these plants extrats to show an antibiosis. Five extracts (EAFQ, SM1, SM12, SM16, SA1) shown positive activity. The extract EAFQ expressed bactericide activity on C. michiganense. It suggests the possibility of using these actives substances in natura or as a model to synthesize industrialized products, intendind field utilization.

Improving the affinity of tomato grafted on Solanum torvum using an intermediate rootstock

Most of the interspecific rootstocks (Lycopersicum esculentum × L. hirsutum) used in grafted Spanish tomato crops are resistant to Meloidogyne nematodes, but the 'Mi' resistance gene does not work well at high soil temperatures. Ralstonia solanacearum is a bacterial disease usual in tropical areas, but recently identified with low incidence in several European countries. This disease could be controlled by grafting tomato on Solanum torvum, which is also resistant to Meloidogyne. However, S. torvum and tomato have low grafting affinity, which could be improved using an intermediate rootstock. Some cultivars of eggplant have a relatively good affinity with tomato and complete affinity with S. torvum. In this study we compared two tomato cultivars (one resistant to Verticillium dalihae, Fusarium oxysporum v. lycopersici race 2 and Meloidogyne spp., and one non-resistant) grafted onto 'Beaufort' (Lycopersicum esculentum × L. hirsutum), 'Torvum Vigor' (Solanum torvum) and also with an intermediate grafting of eggplant ('Cristal') between tomato and S. torvum, with nongrafted plants as controls. This arrangement was carried out in two cropping cycles (winter-spring and summer-autumn). In both cycles, plants grafted onto S. torvum, both single or double grafted, yielded less than those grafted onto 'Beaufort' or nongrafted plants. In the spring cycle, no differences were found between single and double-grafted plants using S. torvum rootstocks, but in the autumn cycle double grafted plants had higher yields than the single grafted plants. The severity of nematode infections, in terms of reducing yields, and/or hypothetical infections of Ralstonia, will determine the utility of this technique in tomato production.

The role of prophage in plant-pathogenic bacteria

A diverse set of phage lineages is associated with the bacterial plant-pathogen genomes sequenced to date. Analysis of 37 genomes revealed 5,169 potential genes (approximately 4.3 Mbp) of phage origin, and at least 50 had no function assigned or are nonessential to phage biology. Some phytopathogens have transcriptionally active prophage genes under conditions that mimic plant infection, suggesting an association between plant disease and prophage transcriptional modulation. The role of prophages within genomes for cell biology varies. For pathogens such as Pectobacterium, Pseudomonas, Ralstonia, and Streptomyces, involvement of prophage in disease symptoms has been demonstrated. In Xylella and Xanthomonas, prophage activity is associated with genome rearrangements and strain differentiation. For other pathogens, prophage roles are yet to be established. This review integrates available information in a unique interface (http://propnav.esalq.usp.br) that may be assessed to improve research in prophage biology and its association with genome evolution and pathogenicity. © Copyright ©2013 by Annual Reviews. All rights reserved.

Opportunistic pathogens and elements of the resistome that are common in bottled mineral water support the need for continuous surveillance

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Resposta enzimática, fisiológica e produtiva do tomateiro e desempenho de porta enxertos resistentes à murcha bacteriana

Pós-graduação em Agronomia (Horticultura) - FCA