RESUMO
The chemical management of the black leaf streak disease in banana caused by Mycosphaerella fijiensis (Morelet) requires numerous applications of fungicides per year. However this has led to fungicide resistance in the field. The present study evaluated the activities of six fungicides against the mycelial growth by determination of EC50 values of strains collected from fields with different fungicide management programs: Rustic management (RM) without applications and Intensive management (IM) more than 25 fungicide application/year. Results showed a decreased sensitivity to all fungicides in isolates collected from IM. Means of EC50 values in mg L-1 for RM and IM were: 13.25 ± 18.24 and 51.58 ± 46.14 for azoxystrobin, 81.40 ± 56.50 and 1.8575 ± 2.11 for carbendazim, 1.225 ± 0.945 and 10.01 ± 8.55 for propiconazole, 220 ± 67.66 vs. 368 ± 62.76 for vinclozolin, 9.862 ± 3.24 and 54.5 ± 21.08 for fludioxonil, 49.2125 ± 34.11 and 112.25 ± 51.20 for mancozeb. A molecular analysis for β-tubulin revealed a mutation at codon 198 in these strains having an EC50 greater than 10 mg L-1 for carbendazim. Our data indicate a consistency between fungicide resistance and intensive chemical management in banana fields, however indicative values for resistance were also found in strains collected from rustic fields, suggesting that proximity among fields may be causing a fungus interchange, where rustic fields are breeding grounds for development of resistant strains. Urgent actions are required in order to avoid fungicide resistance in Mexican populations of M. fijiensis due to fungicide management practices.
Assuntos
Ascomicetos/efeitos dos fármacos , Farmacorresistência Fúngica , Fungicidas Industriais/farmacologia , Musa/microbiologia , Doenças das Plantas/microbiologia , Ascomicetos/genética , Ascomicetos/isolamento & purificação , Uso de Medicamentos , México , Mutação de Sentido Incorreto , Doenças das Plantas/prevenção & controle , Doenças das Plantas/terapia , Tubulina (Proteína)/genéticaRESUMO
Agave tequilana Weber var. 'Azul' is grown for the production of tequila, inulin and syrup. Diverse bacteria inhabit plant tissues and play a crucial role for plant health and growth. In this study culturable endophytic bacteria were extracted from leaf bases of 100 healthy Agave tequilana plants. In plant tissue bacteria occurred at mean population densities of 3 million CFU/g of fresh plant tissue. Three hundred endophytic strains were isolated and 16s rDNA sequences grouped the bacteria into eight different taxa that shared high homology with other known sequences. Bacterial endophytes were identified as Acinectobacter sp., A. baumanii, A. bereziniae, Cronobacter sakazakii, Enterobacter hormaechei, Bacillus sp. Klebsiella oxytoca, Pseudomonas sp., Enterococcus casseliflavus, Leuconostoc mesenteroides subsp. mesenteroides and Gluconobacter oxydans. Isolates were confirmed to be plant growth promoting bacteria (PGPB) by their capacities for nitrogen fixation, auxin production, phosphate solubilization, or antagonism against Fusarium oxysporum AC132. E. casseliflavus JM47 and K. oxytoca JM26 secreted the highest concentrations of IAA. The endophyte Acinectobacter sp. JM58 exhibited the maximum values for nitrogen fixation and phosphate solubilization index (PSI). Inhibition of fungi was found in Pseudomonas sp. JM9p and K. oxytoca JM26. Bacterial endophytes show promise for use as bio-inoculants for agave cultivation. Use of endophytes to enhance cultivation of agave may be particularly important for plants produced by micropropagation techniques, where native endophytes may have been lost.
Assuntos
Agave/microbiologia , Bactérias/classificação , Bactérias/metabolismo , Endófitos/classificação , Endófitos/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Folhas de Planta/microbiologia , Bactérias/isolamento & purificação , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Endófitos/isolamento & purificação , Dados de Sequência Molecular , Regiões Promotoras Genéticas , /genética , Análise de Sequência de DNARESUMO
La paquidermodactilia (PDD) es una forma rara y benigna de fibromatosis digital. Se caracteriza por un engrosamiento asintomático de los tejidos blandos en las caras laterales de las articulaciones interfalángicas proximales de las manos y a veces puede confundirse con algunas enfermedades reumáticas. Los cambios visibles en la resonancia magnética no han sido descritos hasta ahora en la bibliografía médica. Presentamos un caso de PDD en un varón de 19 años y describimos los hallazgos radiológicos en la radiografía simple y en la resonancia magnética. Asimismo, se discute brevemente la PDD(AU)
Pachydermodactyly (PDD) is a rare, benign form of digital fibromatosis characterized by an asymptomatic soft-tissue swelling affecting the skin of the lateral aspects of the proximal interphalangeal joints of the fingers, and sometimes can be misdiagnosed with some rheumatic conditions. Magnetic resonance images changes have not been described in any of the case reports in the literature. We report here a case of PDD in a 19-year-old male and we describe its findings on X-ray and magnetic resonance images. We briefly discuss PDD(AU)