Ilka Márcia Ribeiro de Souza Serra

Scytalidium lignicola em mandioca: ocorrência no Estado do Maranhão e reação de cultivares ao patógeno

Universidade Estadual do Maranhao, Departamento de Fitotecnia e Fitossanidade / Nucleo de Biotecnologia Agronomica, CEP 65041-970, SaoLuis/MA.Autor para correspondencia: Ilka Marcia Ribeiro de Souza Serra ( ilka.tt@gmail.com)Data de chegada: 31/10/2008. Aceito para publicacao em: 15/06/2009. 1626A podridao radicular, causada principalmente, por

Molecular Analysis in the differentiation of Colletotrichum gloeosporioides isolates from the cashew and mango trees

The aim of the present work was to analyze the molecular methods in the differentiation of Colletotrichum gloeosporioides isolates obtained from the cashew and mango trees. The different molecular taxonomic methods used proved to be efficient regarding intraspecific characterization. Similarly, molecular methods also proved to be efficient in differentiation of the C. gloeosporioides isolates in relation to host specificity. In the analysis of the ITS sequence of the ribosomal DNA, all the isolates amplified with the CgInt and ITS4 primers, confirming that they pertained to C. gloeosporioides. The results from this study suggested that methods based on the pathogenicity, isozyme analysis and RAPD were effective in differentiating C. gloeosporioides isolates from the cashew and mango trees.

Diversidade fenotípica e patogênica de Colletotrichum, agente causal da antracnose em mangueira, e identificação de espécie

The present work aimed to study the phenotypic and pathogenic diversity of 40 Colletotrichum isolates obtained from mango trees in the Northeast of Brazil and to identify different species of this pathogen, incitant of anthracnose, through the analysis of the ITS sequence of the ribosomal DNA. As for the morphologic and cultural characterization, the colonies of the isolates presented diversity in relation to color and aspect, being more common the color white-ash, characteristic of C. gloeosporioides. Expressive variations were not observed in the morphology of the 40 isolates. The conidia were predominantly hyaline and unicellular varying in shape from rod to cylindrical. All isolates produced appressoria of different shapes and in different amounts, and 10 isolates showed setae. In relation to mycelial growth and growth rate the isolates were classified in seven groups. Twenty-two isolates exhibited growth rate >10mm/day, considered typical of C. gloeosporioides species. The isolates were pathogenic to detached leaves of mango, inducing anthracnose symptoms such as dark lesions slightly depressed, and presenting variations of aggressiveness. In the specific identification based on the analysis of the ITS sequence of the ribosomal DNA, 36 isolates amplified with the primer CgInt, specific for C. gloeosporioides and with the primer ITS4. Isolates CM1, CM4, CM5 and CM10 did not amplify products for none of the specific primers, being identified as Colletotrichum spp. The results of this work demonstrate that Colletotrichum isolates obtained from mango trees present large morphophysiologic and pathogenic variability, and also that, possibly exists more than one species of Colletotrichum that causes anthracnose in mango trees in the Northeast of Brazil.

Caracterização fisiológica, patogênica e análise isoenzimática de isolados monospóricos e multispóricos de Colletotrichum gloeosporioides.

Monosporic isolates of Colletotrichum gloeosporioides obtained from six cashew and mango trees multisporic isolates were characterized for colony morphology, mycelial growth on BDA, pathogenicity and isozyme analysis. The colonies of multisporic isolates presented diversity of color and aspect, but expressive morphological variations were not observed in 60 monosporic isolates compared to their respective multisporic. Only in two isolates it was possible to observe different morphologic characteristics. All the studied isolates showed good growth on BDA until six days after incubation. Some monosporic isolates obtained from four cashew and mango multisporic ones showed heterogeneous mycelial growth. Pathogenicity was the variable that best characterized the variation between monosporic and multisporic isolates of C. gloeosporioides. Different aggressiveness levels were observed among and within monosporic and multisporic isolates. In the analysis of isozymes, the electrophoretical patterns of isoesterases showed no variation among the monosporic isolates and the parental multisporic ones. The results of this work suggest that the selection of the C. gloeosporioides type isolate for studies on cashew and mango should be preceded by a comparison between monosporic and multisporic isolates based upon mycelial growth and pathogenicity.

Eficiência de produtos naturais no controle de Colletotrichum gloeosporioides em pimenta na pós colheita

The aim of this study was to evaluate the effect of different natural products on the expression of resistance to Colletotrichum gloeosporioides, the etiologic agent of anthracnose, in postharvest pepper fruits. The products acadian®, biopirol®, neemseto®, chitosan and rocksil® were applied at 48 and 72 hours before the pathogen inoculation, in independent treatments, using two doses for each inducer. There was a decrease in the pathogen development for all treatments, statistically differing from the control. At the first application time (48h), treatments with biopirol® followed by acadian® at larger doses led to smaller anthracnose lesions in relation to the remaining treatments at that period. At the second application time (72h), acadian® was the only product to show a significant effect, compared to the other treatments. The obtained results demonstrate the potential of natural inducers to control anthracnose in postharvest pepper fruits.

Effect of Ascophyllum nodosum seaweed extract on post-harvest 'Tommy Atkins’ mangoes

The aim of this study was to determine the effect of Ascophyllum nodosum extract (AN), applied in different doses on the physicochemical characteristics of post-harvest ‘Tommy Atkins’ mangoes. The selected mango fruits were treated with different extract concentrations (0%, 0.1%, 0.3%, 0.5% and 1.0%) and stored for 12 days at 25±2 °C and 75±5% RH. Every 3 days, fruit mass loss (PM), color angle (Hue) (AH), firmness, pH, titratable acidity (AT), content of total soluble solids in pulp (°Brix) and content of carbohydrates in shell were assessed. The experiments were carried out in CRD in a 5 x 5 factorial arrangement (concentrations x days of storage) with four replications. AN was effective in preventing PM, with a reduction of up to 40.2%, as observed at concentration 0.1% compared to control. There were no differences among concentrations on AH, however, all of them differed significantly from control with higher AH, especially on the 12nd day. Fruit firmness was lower in control, the pH increased with the storage time and AT decreased. For all these parameters, mangoes treated with the extract differed from control. The pulp sample °Brix increased with the storage time as well as the content of reducing sugars, with consequent reduction of non-reducing sugars in fruit shell. These tests indicate the possibility of using AN as an alternative management in preserving mangoes in the post-harvest stage.