Daniel Dias Rosa

PR gene families of citrus: their organ specific-biotic and abiotic inducible expression profiles based on ESTs approach

In silico expression profiles, of the discovered 3,103 citrus ESTs putatively encoding for PR protein families (PR-1 to PR-17), were evaluated using the Brazil citrus genome EST CitEST/database. Hierarchical clustering was displayed to identify similarities in expression patterns among citrus PR-like gene families (PRlgf) in 33 selected cDNA libraries. In this way, PRlgf preferentially expressed by organ and citrus species, and library conditions were highlighted. Changes in expression profiles of clusters for each of the 17 PRlgf expressed in organs infected by pathogens or drought-stressed citrus species were displayed for relative suppression or induction gene expression in relation to the counterpart control. Overall, few PRlgf showed expression 2-fold higher in pathogen-infected than in uninfected organs, even though the differential expression profiles displayed have been quite diverse among studied species and organs. Furthermore, an insight into some contigs from four PRlgf pointed out putative members of multigene families. They appear to be evolutionarily conserved within citrus species and/or organ- or stress-specifically expressed. Our results represent a starting point regarding the extent of expression pattern differences underlying PRlgf expression and reveal genes that may prove to be useful in studies regarding biotechnological approaches or citrus resistance markers.

Dinâmica temporal e espacial da begomovirose causada por Tomato yellow vein streak virus em tomateiro na região de Campinas-SP

The purpose of the present work was the characterization of the temporal and spatial pattern of Tomato yellow vein streak virus (ToYVSV), transmitted by the whitefly Bemisia tabaci, in tomato crops under field and greenhouse conditions, in Sumare and Elias Fausto counties, respectively, State of Sao Paulo, Brazil. A total of 4,032 plants of cultivar Alambra, distributed in eight randomized blocks, were evaluated under field conditions. Evaluations in greenhouses were performed on 6,016 plants of cultivar Ikram. Plants were transplanted into eight greenhouses, in a staggered manner. Evaluations were based on typical symptoms induced by this begomovirus. The identification of the virus species was based on the analysis of the nucleotide sequence of part of the DNA-A (810 bp), which included the AV1 and AC3 genes. The incidence of the disease progressed very slowly under field conditions, coming from a minimum of 0.002 (proportion of symptomatic plants) to a maximum of 0.0497. In spite of this, border effect was observed, since the average of diseased plants in the peripheric blocks was 2.1 times higher than in the inner blocks. The disease progress curve was linear, indicating that newer infections were mainly due to the constant influx of viruliferous whiteflies coming from outside sources of inoculum. The percentage of diseased plants in tomatoes grown under greenhouse conditions was enormously influenced by the time of planting, varying from 4.8% to 69.3%. The spatial distribution of symptomatic tomato plants in these crops was aggregated. Apparently, this pattern was not due to secondary infections, but a result of aggregation of diseased plants near the periphery of the greenhouses. Based on these results, it is suggested that the elimination of sources of inoculum represented by old tomato crops and infected weed hosts is one of the most important practices for disease management.

Efeitos da simulação da solarização do solo com materiais vegetais sobre o crescimento micelial de fungos fitopatogênicos habitantes do solo

A incorporacao de materiais vegetais especificos associados a solarizacao do solo tem sido um avanco promissor no controle de fungos fitopatogenicos habitantes do solo. O objetivo do trabalho foi avaliar determinados efeitos da incorporacao e decomposicao de brocolis, mamona, mandioca brava e mansa, no solo, em condicoes de microcosmo mantido em BOD (37±2oC), sobre o micelio de Fusarium oxysporum f. sp. lycopersici Raca 2, Macrophomina phaseolina, Rhizoctonia solani AG-4 HGI e de Sclerotium rolfsii. Assim, quatro ensaios identicos foram instalados em conjunto de microcosmos, com cinco tratamentos e quatro periodos de tempo diferentes e independentes (7, 14, 21 e 28 dias). O parâmetro avaliado foi os efeitos inocuo, fungistatico e fungicida dos tratamentos sobre o micelio dos fungos. Verificou-se efeito fungistatico e fungicida no crescimento micelial de F. oxysporum f. sp. lycopersici Raca 2, R. solani AG-4 HGI e de S. rolfsii. Os fungos que apresentaram efeito fungistatico apresentaram uma velocidade media de crescimento micelial inferior ao controle geral, que consistiu na incubacao dos fungos em temperatura de 25±2oC. O efeito fungicida ocorreu aos 21 dias de incubacao para F. oxysporum e R. solani e aos 28 dias para S. rolfsii. Para M. phaseolina, observou-se apenas efeito inocuo. Associacao da temperatura de 37±2oC mais o periodo de tempo dos tratamentos foi o fator responsavel pelos efeitos fungistatico e fungicida no micelio dos fitopatogenos estudados. Essa associacao tambem interferiu na velocidade do crescimento micelial dos fungos que apresentaram efeito fungistatico.

First report of Colletotrichum gloeosporioides on Hylocereus megalanthus in Brazil

Reddish-orange spots with chlorotic halos were detected in stems and fruits of yellow pitahaya (Hylocereus megalanthus) in Botucatu region, Brazil, and Colletotrichum gloeosporioides was identified as the causal agent. This is the first Brazilian report on Colletotrichum gloeosporioides (Penz.) Penz. & Sacc leading to anthracnose in pitahaya plants.

Produção de enzimas extracelulares por Fusarium solani de maracujazeiro amarelo

RESUMO Uma das principais doencas do maracujazeiro, na maioria dos estados produtores do Brasil, e a podridao do colo, causada por Fusarium solani. Pouco se sabe a respeito da fisiologia deste patogeno do maracujazeiro amarelo, principalmente quanto a producao de enzimas extracelulares. O objetivo do presente trabalho foi verificar, em meios de cultura individuais e apropriados, a producao das enzimas extracelulares amilase, lipase, celulase, proteases (caseinase e gelatinase), lacase (oxidase) e catalase por isolados de F. solani, provenientes de maracujazeiro amarelo. O delineamento experimental adotado foi o inteiramente casualizado, em esquema de dois fatores (nove isolados versus sete enzimas), com tres repeticoes. Todos os isolados de F. solani produziram, de maneira semiquantitativa, as enzimas extracelulares amilase, lipase, celulase, caseinase (protease) e lacase (oxidase). No entanto, a quantidade produzida de cada enzima foi significativamente diferente entre os isolados. As enzimas extracelulares gelatinase (protease) e catalase foram produzidas em pouca quantidade e de maneira igual por todos os isolados do fungo. Palavras-chave: Passiflora sp., atividade enzimatica, fungos de solo, patogeno de planta.

Ocorrência de Dictyla monotropidia Stål (Hemiptera: Tingidae) em Cordia verbenacea Al. DC no Brasil

Recently, Dictyla monotropidia Stal was observed feeding on plants of black sage (Cordia verbenacea Al. DC). The colonies of this insect were observed on abaxial surface of leaves, with nymphs and adults sucking the phloem sieve, causing spot, yellow aspect and leaf fall. D. monotropidia was already related as pest in other Cordia species in countries of Central and South America. Although, this is the first report of this insect attacking plants of C. verbenacea in Brazil.

Phytophthora parasitica transcriptome, a new concept in the understanding of the citrus gummosis

Due to the economic importance of gummosis disease for the citriculture, studies on P. parasitica-Citrus interaction comprise a significant part in the Brazilian Citrus genome data bank (CitEST). Among them, two cDNA libraries constructed from two different growth conditions of the P. parasitica pathogen are included which has generated the PP/CitEST database (CitEST - Center APTA Citros Sylvio Moreira/IAC- Millennium Institute). Through this genomic approach and clustering analyses the following has been observed: out of a total of 13,285 available in the Phytophthora parasitica database, a group of 4,567 clusters was formed, comprising 2,649 singlets and 1,918 contigs. Out of a total of 4,567 possible genes, only 2,651 clusters were categorized; among them, only 4.3% shared sequence similarities with pathogenicity factors and defense. Some of these possible genes (103) corresponding to 421 ESTs, were characterized by phylogenetic analysis and discussed. A comparison made with the COGEME database has shown homology which may be part of an evolutionary pathogenicity pathway present in Phytophthora and also in other fungi. Many of the genes which were identified here, which may encode proteins associated to mechanisms of citrus gummosis pathogenicity, represent only one facet of the pathogen-host Phytophthora - Citrus interaction.

Avaliação de fungicidas, óleos essenciais e agentes biológicos no controle de Amphobotrys ricini em mamoneira (Ricinus communis L.)

The castor bean (Ricinus communis L.) is a tropical oilseed species, and the oil extracted from its seeds is one of the most versatile oils in the nature, showing various industrial uses. Even though it is a rustic species, the castor bean is subjected to several diseases such as the gray mold, caused by the fungus Amphobotrys ricini. Genetic breeding would be the best alternative for the disease control, but a long time is required to obtain resistant cultivars. Thus, the use of control strategies based on chemical, alternative or biological methods shows viable in the short term. The aim of this study was to investigate gray mold control efficiency, in castor bean crop, using chemical, alternative and biological methods. The pathogen control efficiency was evaluated both in vitro and in vivo using fungicides, essential oils and biological control agents. As regards the in vitro inhibition of the pathogen mycelial growth, the best treatments with essential oils were those based on C. martini and C. zeylanicum at all five tested concentrations. For both oils, the average diameter of colonies was 0.7 cm against 4.79 cm for the control treatment. For the fungicides, at all four tested levels, the most efficient active ingredients were methyl tiophanate, carbendazim, tebuconazole and iprodione. The ED50 of these fungicides was <1uL/L, yielding 100% mycelial growth inhibition at all concentrations. As to the inhibition of A. ricini conidium germination, the fungicides tebuconazole and chlorotanolyl were the best at all tested concentrations, and the average of germinated conidia with these fungicides was 0.0 and 0.15%, respectively, against 100% for the control treatment. In the field, treatment with the fungicide iprodione was the best for the disease control when compared to biological and alternative treatments. Under field conditions, the average disease severity for the treatment with iprodione was 15.76% against 95.81% for the inoculated control.

Caracterização patogênica e molecular de Plasmodiophora brassicae

Few studies have been conducted with clubroot disease in Brazil, caused by Plasmodiophora brassicae. Tests on severity of disease using different populations were carried out in brassica species (cauliflower, susceptible Chinese cabbage, resistant Chinese cabbage, broccoli, and cabbage). P. brassicae populations were obtained from infected roots in several commercial production regions in Brazil. Severity tests were conducted under greenhouse conditions (25±2oC) with inoculations (2 mL) of spore suspension at concentration of 107 spores. mL-1, applied in the collar root of each plant. Disease evaluations were performed 35 days after inoculation. DNA extraction and PCR-RAPD analyses for these populations were conducted to compare genetic traits. The populations obtained from the regions of Carandai MG and Colombo PR was more aggressive, and cause symptoms even in cultivars considered resistant. However, no specific genetic pattern was observed as to the place of origin or aggressiveness.

Método rápido de extração de DNA de bactérias

A fast extraction method for bacteria DNA was developed. Unlike some other methods, the method does not require enzymes like lysozime and proteinase K. Carbonate silicate (carborundum) was used to break cell more efficiently. This method is fast, simple and more economic when compared to the previously report ones. The prepared DNA from bacteria has good quality and amount.