Maria Angélica Guimarães Barbosa

Five Colletotrichum species are responsible for mango anthracnose in northeastern Brazil

Colletotrichum species are the most important and widespread form of decay affecting mango fruit worldwide. In this study, Colletotrichum species associated with fruit anthracnose isolated from mango in northeastern Brazil were subject to molecular and morphological analyses. The partial sequences of the glyceraldehyde-3-phosphate dehydrogenase gene of 143 Colletotrichum isolates was amplified, as an initial measure of genetic diversity. A subset of 47 isolates, selected to represent the range of genetic diversity and geographic origin, were further sequenced using the partial actin, β-tubulin, calmodulin, glutamine synthetase genes and rDNA-ITS region. The multilocus sequence analysis, together with a critical examination of the phenotypic characters, revealed four previously described species (Colletotrichum asianum, Colletotrichum fructicola, Colletotrichum tropicale and Colletotrichum karstii) and one new species. The new species is introduced as Colletotrichum dianesei and formally described, illustrated and compared with similar taxa. Only C. asianum and C. karstii have previously been reported from mango, while the other species represent the first report associated with the mango fruits worldwide. All species are reported for the first time associated with the mango fruits in Brazil.

Antagonism of Trichoderma species on Cladosporium herbarum and their enzimatic characterization

The verrucose caused by Cladosporium herbarum reduces production and quality of Passion fruit (Passiflora edulis Sims.), a largely consumed tropical fruit. This work aimed to investigate the antagonism of Trichoderma species (T. polysporum, T. koningii, T. viride and T. harzianum) against Cladosporium herbarum, and to study the production of extracellular hydrolytic enzymes by the pathogen and the antagonists. The results showed considerable antagonistic potential for the biocontrol of C. herbarum isolates by all Trichoderma species, except T. koningii. The most distinguished effect was observed for T. polysporum. In relation to the pattern of esterase obtained by electrophoresis in poliacrylamyde gel, the major activity presented by the isolates was observed after five days of incubation. The C. herbarum isolates produced extracellular enzymes, lipase, pectinase, cellulase, and protease, all possibly related to the infection process. Amylase excretion, not known to be associated with phytopathogens, was detected in Trichoderma species, but not in C. herbarum. In addition to amylase, all Trichoderma species tested produced also extracellular cellulase and pectinase, except T. koningii in relation to the latter enzyme. The demonstration of various esterase isoenzymes in zymograms of the Trichoderma species and C. herbarum isolates was markedly improved by washing the mycelia with detergents or EDTA. This fact suggested that a major fraction of extracelular enzymes may remain attached to outside fungal cell wall after being excreted.

Physiological cost of induced resistance in cotton plants at different nitrogen levels

Resistance induction through the use of chemical inducers often results in physiological costs to the plant. In this study, induced resistance in cotton plants was evaluated with regard to physiological costs in a cultivar susceptible to Colletotrichum gossypii var. cephalosporioides (CNPA GO 2002 - 7997). Plants were cultivated in substrates with two levels of nitrogen and received two applications of acibenzolar-S-methyl (ASM), jasmonic acid (JA) and Agro-Mos® (AM) disease resistance inducers. Plant height (H), internodal length (IL), shoot fresh weight (SFW), root fresh weight (RFW), shoot dry weight (SDW) and root dry weight (RDW) were evaluated. The activity of the phenylalanine ammonia lyase (PAL) and peroxidase (POX) was also determined. The plants treated with ASM presented high physiological costs with an accentuated reduction in H, SFW and SDW, whereas those treated with JA exhibited a significant increase in SDW, and did not significantly differ from H and IL. In the potting mix supplemented with nitrogen, all inducers differed from the control treatment regarding to internodal length, whereas only ASM and AM presented a significant difference between one another in the potting mix without the addition of nitrogen. Significant correlations (P=0.05) were found for most of the variables analyzed, with greater correlations observed between SFW and SDW (0.94); IL and H (0.74); SFW and H (0.70); and SDW and H (0.70). ASM induced the least amount of PAL activity, significantly differing from the remaining treatments. Greater POX activity was observed in ASM, which significantly differed from the control. AM and JA, however, presented lower activity than the control with regard to these enzymes, and it was not possible to confirm induction resistance in these two treatments.

Characterization of Phaeoacremonium isolates associated with Petri disease of table grape in Northeastern Brazil, with description of Phaeoacremonium nordesticola sp. nov.

This study aims to identify and characterize species of Phaeoacremonium associated with Petri disease of table grapes in three regions in the Northeastern Brazil, to investigate the distribution of the species in these regions and to evaluate their pathogenicity and aggressiveness in excised green shoots of table grapes. Fungal identifications were made using a combination of morphology together with a phylogenetic analysis based on portions of the β-tubulin (TUB2) and actin (ACT) genes. Three species of Phaeoacremonium (Pm.) were identified: Pm. minimum, Pm. nordesticola sp. nov. and Pm. parasiticum. Phaeoacremonium minimum and Pm. parasiticum had previously been reported in grapevine. Phaeoacremonium minimum was the most prevalent species. All species of Phaeoacremonium were pathogenic on detached shoots of table grape, with Pm. minimum being the most aggressive.

Induction of resistance to Xanthomonas campestris pv. viticola in grapevine plants.

The objective of this work was to evaluate the effect of Saccharomyces cerevisiae (SC), Acibenzolar-S-Methyl (ASM), organic acids and polyphenols (OAP) and potassium silicate (SiK) on protecting grapevine plants (cv. Redglobe) from Xanthomonas campestris pv. viticola. Four application rates for each product (SC at 2.0, 2.50, 3.0, 3.50 and 4.0 mL 100 L-1; ASM and OAP at 2.50, 3.00, 3.50, 4.50 and 6.00 mL 100 L-1 and SiK at 5.00, 6.50, 7.50 and 8.50 mL 100 L-1) in different application times (0, 5, 10, and 15 days before inoculation), and the enzymatic activity of peroxidases, phenylalanine ammonia-lyase and ?-1,3 glucanases were evaluated. Plants were inoculated with a bacterial suspension of 5 x 108 CFU mL-1 by rubbing with gauze. The epidemiological variables incidence (INC), severity (SEV) and area under the disease progress curve (AUDPC) were assessed. The treatment with ASM had the lowest averages of INC (38%) and SEV (1.52%) from 3 g 100 L-1. The application of 4.5 mL 100 L-1 of OAP reduced the plant disease in 52% of INC and 2.45% of SEV. SiK and SC presented no significant reduction in these variables compared to control. The ASM applied 15 days before the inoculation (DBI) reduced the disease in 91.31% and the APO in 73.34%, while SC and SiK reduced the disease in 67.49 and 60.11%, respectively, with applications at 5 DBI. There was no increase of peroxidase activity in any of the treatments. There was a significant increase in activity of ?-1,3 glucanases and phenylalanine ammonia-lyase in plants treated with ASM at 15 DBI, indicating an influence on the induction of resistance of plants to this disease.ABSTRACT Peach is much appreciated by consumers and its popularity is mainly related with organoleptic characteristics. However, with emergence of concepts of functional foods (health promoters), there is high interest to study and to quantify the biochemical components of fruits. The aim of this work was to perform the biochemical characterization of peach genotypes, evaluating the genetic diversity and selecting those with desirable biochemical qualities for use as parents in future breeding programs. The experiment was carried out at the Laboratory of Plant Physiology UTFPR Campus of Dois Vizinhos, PR (Brazil), with fruits from 26 and 29 peach genotypes (Prunus persica) in the 2009/2010 and 2010/2011 crop years, respectively. The experimental design was entirely randomized, considering each genotype as treatment, using four replicates and four fruits per plot. Total and reducing sugars, total proteins, amino acids, total phenols, anthocyanins, flavonoids and phenylalanine ammonia-lyase enzyme activity (PAL) in fruits were evaluated. According to the results of two crop years, ‘Cascata 967’, ‘Conserva 985’, ‘Kampai’, ‘Tropic Snow’ and ‘Cascata 1055’ were selected as those with the highest levels of these compounds.O pessego e uma fruta muito apreciada, cuja popularidade e decorrente principalmente de seu sabor agradavel. Entretanto, com o surgimento dos conceitos de alimentos funcionais (com propriedades promotoras de saude), surgira interesse maior em estudar e quantificar os componentes bioquimicos das frutas. Os objetivos deste trabalho foram caracterizar bioquimicamente frutos de genotipos de pessegueiro, e selecionar aqueles com qualidades bioquimicas desejaveis para sua futura insercao como genitores em programas de melhoramento. O experimento foi conduzido no Laboratorio de Fisiologia Vegetal e Bioquimica da UTFPR - Campus Dois Vizinhos, com frutos de 26 e 29 genotipos de pessegueiro ( Prunus persica ), provenientes dos ciclos produtivos 2009/2010 e 2010/2011, respectivamente. O delineamento experimental foi inteiramente casualizado considerando-se cada genotipo como tratamento, utilizando-se quatro repeticoes de quatro frutos. Foram analisados os acucares totais e redutores, proteinas totais, aminoacidos, fenois totais, antocianinas, flavonoides e atividade da enzima fenilalanina amonia-liase (FAL) dos frutos. Os pessegos foram caracterizados bioquimicamente, selecionando-se como superiores, na media dos dois ciclos produtivos os genotipos ‘Cascata 967’, ‘Conserva 985’, ‘Kampai’, ‘Tropic Snow’, e ‘Cascata 1055’.

Efeito do tratamento de bacelos de videira 'Red Globe' no controle do cancro bacteriano causado por Xanthomonas campestris pv. viticola

The spread of Xanthomonas campestris pv. viticola (Xcv), causal agent of grapevine bacterial canker, occurs among other ways, through infected plants and grapevine cuttings. It was studied how to obtain propagation material free of Xcv testing the effectiveness of treatments of cuttings using thermotherapy, bactericides and sanitizers. The Xcv isolates were tested for pathogenicity and in vitro sensitivity to bactericides and sanitizers at different concentrations. The eradication of Xcv on cuttings was tested in experiments with thermotherapy (50oC for 30 and 40 min; 53oC for 5 and 10 min); bactericides [oxytetracycline+copper sulphate (150+2000, 165+2200, 180+2400 and 195+2600 mg L-1 of H2O) and oxytetracycline (600, 700, 800 and 900 mg L-1)] and sanitizers [dodecyldimethyl ammonium chloride (600, 1200, 1800, 2400 and 3000 µl L-1) sodium hypochlorite (5000, 10000, 20000, 30000 and 40000 µl L-1) and benzalkonium chloride (125, 167, 250, 334 and 500 µl L-1)]. We evaluated the incubation period, the incidence and severity of disease. The bactericidal oxytetracycline and sanitizers dodecyldimethyl ammonium chloride and sodium hypochlorite provided the largest zones of inhibition, in vitro. However, despite the several treatments tested we cannot recommend an efficient condition of temperature/time, and concentrations of bactericides and sanitizers capable of eradicating Xcv from infected grapevine cuttings, thus confirming their great importance for the spread of grapevine bacterial canker.

Identificação de potenciais plantas hospedeiras alternativas de Xanthomonas campestris pv. viticola

Este estudo teve como objetivo identificar possiveis hospedeiras alternativas de Xanthomonas campestris pv. viticola (Xcv), visando a fornecer subsidios para o manejo do cancro bacteriano da videira. Vinte e seis especies vegetais foram inoculadas artificialmente com o isolado Xcv3 e mantidas em condicoes de casa de vegetacao, sendo avaliada a evolucao sintomatologica da doenca, como manchas necroticas angulares e lesoes nas nervuras. O Xcv3 foi reisolado a partir de cada hospedeiro alternativo com sintomas, sendo identificado por PCR (Polymerase Chain Reaction), com iniciadores especificos. As especies inoculadas que apresentaram os sintomas tipicos da doenca foram Glycine sp., Senna obtusifolia, Desmodium discolor, Amaranthus deflexus, Azadirachta indica, Solanum lycopersicum e Vigna unguiculata. As especies da familia Poaceae, Bidens pilosa, Emilia fosbergii, Praxelis pauciflora, Macroptilium lathyroides e Portulaca oleracea nao apresentaram sintomas durante o periodo da avaliacao.