Rildo Sartori Barbosa Coelho

Ocorrência de doenças em plantas ornamentais tropicais no Estado de Pernambuco

The climatic conditions in which tropical flowers are grown in Northeast Brazil, related to rainfall, humidity, temperature and cropping density factors, favor disease occurrence that limit and reduce the quality and yield of flowers. In this survey several diseases caused by fungi and nematodes were observed. Among them were the anthracnose (Colletotrichum gloeosporioides) on Heliconia spp, Etlingera elatior, Tapeinochilos ananassae, causing leaf and inflorescence lesions; leaf spots (Bipolaris spp., Cercospora sp., Curvularia lunata, Glomerella cingulata, Guignardia sp and Deighthoniela torulosa) on Heliconia app, Calathea burle - marx and Musa coccinea; roots and rhizomes rots (Rhizoctonia solani and Fusarium oxysporum f. sp. cubense) on E. elatior and Heliconia chartacea cv. Sex Pink. Phytonematoses, caused by Meloidogyne spp., Radopholus sp. and Helicotylenchus sp. make up one of the main disease problems found in ornamental plants in the State of Pernambuco, usually occurring on Alpinia purpurata, E. elatior, Zingiber spectabiles, Heliconia spp. and Musa spp. Alpinia purpurata was found to be the most susceptible to M. incognita. On the other hand, the low incidence of bacterial wilt (Ralstonia solanacearum race 2) in the flower crop areas was associated with eradication carried out by flower producers.

Indução de resistência a Fusarium oxysporum f. sp. Tracheiphilum em Caupi: eficiência de indutores abióticos e atividade enzimática elicitada

The effect of abiotic inducers in two cowpea cultivars inoculated with Fusarium oxysporum f.sp. tracheiphilum (E. F. Smith) Snyder & Hansen was evaluated in relation to severity, disease control and enzyme activity. Aqueous solution of ASM (5.0 mg/mL), BABA (1.5 mM) or chitosan (2.0 mg/mL) was sprayed on the first pair of leaves of five-day-old cowpea plants, cultivars BR-17 Gurgueia and IPA-206. After seven days of elicitor application, inoculation was carried out with 20 mL of a 1 x 106 conidia/mL suspension of the ISO-PE isolate. Plants were harvested at five and 10 days after inoculation, and the activity of phenylalanine ammonia lyase (PAL), b-1.3-glucanase and peroxidase was analyzed. Significant difference between treatment with inducers and control was verified, mainly for ASM which provided a disease control of 68.9% and 71.59% for BR-17 Gurgueia and IPA-206 cultivars, respectively. ASM showed the best results related to b-1.3-glucanase, peroxidase and PAL and activities, especially for the cultivar IPA-206 five or 10 days. BABA and chitosan differed from the control for PAL and b-1.3-glucanase activity on cultivar IPA-206, five days after inoculation.

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.

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.

Eficiência e atividade enzimática elicitada por metil jasmonato e silicato de potássio em cana-de-açúcar parasitada por Meloidogyne incognita

ABSTRACT The present study had as objective to evaluate methyl jasmonateand potassium silicate effect on Meloidogyne incognita parasitism insugarcane ( Saccharum sp.) variety RB863129 and peroxidase and -1,3-glucanase activity elicited, under greenhouse. The effect of Methyljasmonate and potassium silicate did not affect shoot biomass. Methyljasmonate and potassium silicate significantly decreased eggs number Guimaraes, L.M.P., Pedrosa, E.M.R., Coelho, R.S.B., Couto, E.F., Maranhao, S.R.V.L. & Chaves, A. Efficiency and enzymatic activity elicited bymethyl jasmonate and potassium silicate on sugarcane under Meloidogyne incognita parasitism. Summa Phytopathologica, v.36, n.1, p.11-15, 2010. Keywords: root-knot nematode, Saccharum sp., peroxidase, -1,3-glucanase, resistance induction Palavras-chave adicionais: Nematoide das galhas, Saccharum sp . , peroxidase, -1,3-glucanase, inducao de resistencia RESUMO O presente estudo teve como objetivo avaliar o efeito de metiljasmonato e silicato de potassio sobre o parasitismo de

Resistance Induction for Meloidogyne incognita in Sugarcane through Mineral Organic Fertilizers

The effects of Coda Radimax (CR), Coda Humus-PK (CH) and Coda Vit (CV) on the induction of resistance for Meloidogyne incognita in sugarcane (Saccharum sp.) varieties (RB92579, RB863129, RB867515) through nematode reproduction, plant development and root anatomy analysis, emphasizing the differences of the lignin deposition, and cortex-vascular cylinder proportions were investigated. In 90 days after inoculation with eggs of M. incognita, CR reduced the number of eggs per root system in all the sugarcane varieties; CH and CV reduced eggs density in RB867515; CR increased stalk number in RB92579 and fresh weight of shoots in RB863129 and RB92579; CH increased plant height in RB92579 and fresh weight of shoots in RB92579 and RB867515, CV affected fresh weigh of shoots and roots of RB863129. All the tested compounds did not affect stalk diameter, number and dry weight of shoots. Cross-sections of roots showed no anatomical changes in the M. incognita inoculated tissues.

Genes diferentes podem conferir resistência ao Cowpea severe mosaic virus em caupi

Cowpea (Vigna unguiculata) is an important vegetable crop in Northeast Brazil and has been traditionally cultivated by small farmers. Virus diseases are considered to be the main factor in yield limiting cowpea yield in the region. The severe mosaic disease caused by Cowpea severe mosaic virus (CpSMV), family Comoviridae, genus Comovirus, seems to be one of the most prevalent diseases responsible for high losses. Resistant cultivars may be considered the best alternative for disease control, and several promising sources of resistance such as Macaibo, CNC 0434 cultivars, and the line L 254.008 have been reported. More recent investigations into the genetic basis of these resistant plant genotypes have pointed to similar results, and the inheritance of this resistance has been recognized as monogenic recessive. On the other hand, any research aimed to investigate if the resistance genes are alleles or not. In the present investigation a test was conducted to elucidate this question. Plants of the genotypes Macaibo, CNC 0434 and L 254.008 were bred in reciprocal and direct ways producing six populations. Evaluation of those cowpea genotypes using one isolate of CpSMV indicated that the resistance gene of Macaibo is the same as that for CNC 0434 and distinct from the gene L 254.008 found in that line.

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.

Avaliação de indutores de resistência em algodoeiro a murcha de fusário: atividade enzimática e índice de infecção

Os indutores de resistencia acibenzolar-S-metil, metil jasmonato e fosfato de potassio (K2HPO4), nas concentracoes de 0,2 g/L, 0,1 mL/L e 0,1 M, respectivamente, foram testados em plântulas de algodoeiro (cv. BRS Cedro), para o controle de Fusarium oxysporum f. sp. vasinfectum. Foram realizadas uma e duas aplicacoes com todos os indutores em plântulas com e sem inoculacao do fitopatogeno. Constatou-se que o menor indice de infeccao foi obtido com o uso do metil jasmonato aplicado duas vezes. Amostras de folhas e caule foram avaliadas quantitativamente para as enzimas β-1,3-glucanase, peroxidase e quitinase. As plantas testemunhas sem inoculacao apresentaram as maiores atividades das enzimas peroxidase e β-1,3-glucanase no caule. Nas folhas das plantas que receberam os tratamentos com metil jasmonato (uma aplicacao com inoculacao), a atividade das enzimas peroxidase e quitinase foram as maiores. Nas amostras de caule nao houve atividade detectada da enzima quitinase.

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.