ABSTRACT
Una enfermedad foliar fue detectada en la plantación comercial de Khaya senegalensis con 3 anos de edad, en la localidad de Huimanguillo (Tabasco, México). Mediante la caracterización morfológica y molecular, y por el cumplimiento de los postulados de Koch, se determinó que el agente causal corresponde al hongo Sclerotium coffeicola. Este es el primer reporte de S. coffeicola causando mancha foliar en caoba africana en México.
A foliar disease was detected in the commercial plantation of Khaya senegalen with three years of age in Huimanguillo, Tabasco, Mexico. Through the morphological and molecular characterization and the compliance of the Koch's postulates, it was concluded that the causal agent corresponds to the fungus Sclerotium coffeicola. This is the first report of S. coffeicola causing leaf spot on African mahogany in Mexico.
Subject(s)
Basidiomycota , Meliaceae , MexicoABSTRACT
A foliar disease was detected in the commercial plantation of Khaya senegalensis with three years of age in Huimanguillo, Tabasco, Mexico. Through the morphological and molecular characterization and the compliance of the Koch's postulates, it was concluded that the causal agent corresponds to the fungus Sclerotium coffeicola. This is the first report of S. coffeicola causing leaf spot on African mahogany in Mexico.
Subject(s)
Basidiomycota , Meliaceae , MexicoABSTRACT
Muscodor yucatanensis, an endophytic fungus, was isolated from the leaves of Bursera simaruba (Burseraceae) in a dry, semideciduous tropical forest in the Ecological Reserve El Eden, Quintana Roo, Mexico. We tested the mixture of volatile organic compounds (VOCs) produced by M. yucatanensis for allelochemical effects against other endophytic fungi, phytopathogenic fungi and fungoids, and plants. VOCs were lethal to Guignardia mangifera, Colletotrichum sp., Phomopsis sp., Alternaria solani, Rhizoctonia sp., Phytophthora capsici, and P. parasitica, but had no effect on Fusarium oxysporum, Xylaria sp., the endophytic isolate 120, or M. yucatanensis. VOCs inhibited root elongation in amaranth, tomato, and barnyard grass, particularly those produced during the first 15 days of fungal growth. VOCs were identified by gas chromatography/mass spectrometry and included compounds not previously reported from other Muscodor species and the previously reported compounds octane, 2-methyl butyl acetate, 2-pentyl furan, caryophyllene, and aromadendrene. We also evaluated organic extracts from the culture medium and mycelium of M. yucatanensis on the same endophytes, phytopathogens, and plants. In general, extracts inhibited plants more than endophytic or phytopathogens fungi. G. mangifera was the only organism that was significantly stimulated by both extracts regardless of concentration. Compounds in both organic extracts were identified by gas chromatography/mass spectrometry. We discuss the possible allelopathic role that metabolites of M. yucatanensis play in its ecological interactions with its host plant and other organisms.
Subject(s)
Bursera/chemistry , Pheromones/pharmacology , Plant Roots/drug effects , Volatile Organic Compounds/pharmacology , Xylariales/chemistry , Culture Media, Conditioned/metabolism , Dose-Response Relationship, Drug , Gas Chromatography-Mass Spectrometry , Mexico , Pheromones/classification , Pheromones/isolation & purification , Plant Roots/growth & development , Plant Roots/metabolism , Time Factors , Volatile Organic Compounds/classification , Volatile Organic Compounds/isolation & purificationABSTRACT
Chemical investigation of the mycelium of Edenia gomezpompae, a newly discovered endophytic fungus isolated from the leaves of Callicarpa acuminata (Verbenaceae) collected from the ecological reserve El Eden, Quintana Roo, Mexico, resulted in the isolation of four naphthoquinone spiroketals, including three new compounds and palmarumycin CP2 (4). We elucidated the structures of the metabolites by extensive NMR spectroscopy studies, including DEPT, COSY, NOESY, HSQC, HMBC, and chiroptical methods. The trivial names proposed for these compounds are preussomerin EG1 (1), preussomerin EG2 (2) and preussomerin EG3 (3). In addition, the X-ray data for 4 were obtained. The bioactivity of the mycelial organic extracts and the pure compounds was tested against three endophytic fungi (Colletotrichum sp., Phomopsis sp., and Guignardia manguifera) isolated from the same plant species (C. acuminata, Verbenaceae) and against four economically important phytopathogenic microorganisms (two fungoid oomycetes, Phythophtora capsici and Phythophtora parasitica, and the fungi Fusarium oxysporum and Alternaria solani). Spiroketals 1-3 displayed significant growth inhibition against all the phytopathogens. IC50 values for the four phytopathogens were from 20 to 170 microg/ml. Palmarumycin CP2 (4) was not bioactive against any of the fungi tested. Compound 1 showed the strongest bioactivity. The acetylated derivatives of preussomerin EG1 (1), 1a and 1b, were obtained and their biological activity was tested on endophytes and phytopathogens. Preussomerin EG1 1, 1a and 1b exhibited significant bioactivity against all microorganisms tested with the exception of Alternaria solani. This is the first report of allelochemicals with antifungal activity from the newly discovered endophytic fungus E. gomezpompae.
Subject(s)
Antifungal Agents/pharmacology , Ascomycota/chemistry , Epoxy Compounds/pharmacology , Fungi/drug effects , Heterocyclic Compounds, 4 or More Rings/pharmacology , Naphthalenes/pharmacology , Spiro Compounds/pharmacology , Antifungal Agents/isolation & purification , Antifungal Agents/metabolism , Ascomycota/metabolism , Biological Assay , Crystallography, X-Ray , Culture Media, Conditioned/chemistry , Dose-Response Relationship, Drug , Epoxy Compounds/isolation & purification , Epoxy Compounds/metabolism , Fungi/growth & development , Heterocyclic Compounds, 4 or More Rings/isolation & purification , Heterocyclic Compounds, 4 or More Rings/metabolism , Magnetic Resonance Spectroscopy/methods , Models, Molecular , Molecular Conformation , Naphthalenes/isolation & purification , Naphthalenes/metabolism , Plant Diseases/microbiology , Plant Leaves/microbiology , Spiro Compounds/isolation & purification , Spiro Compounds/metabolism , Stereoisomerism , Verbenaceae/microbiologyABSTRACT
Poroleprieuria gen. nov. is described and illustrated to accommodate P. rogersii in the Xylariaceae, Xylariales. This ascomycete, known only from the type collection, is characterized by reniform, light brown, smooth ascospores with a germ pore; cylindrical, persistent asci lacking an apical apparatus, septate persistent paraphyses, and erumpent, erect, dark brown, fragile, subcylindrical stromata. The characteristics of this xylariaceous fungus were compared with those of some other ascomycetes having superficially similar cylindrical stromata or ascospores with germ pores.
ABSTRACT
In order to evaluate the monophyly of the Phyllachorales from a molecular standpoint and elucidate its phylogenetic relationships with other orders, a segment of the 18S rRNA gene from several representatives of the Phyllachorales, including species of Glomerella, Phyllachora, Coccodiella (=Coccostroma), Sphaerodothis, Ophiodothella, as well as Magnaporthe was sequenced. Maximum Parsimony analysis revealed that the Phyllachorales was a polyphyletic assemblage of taxa. None of the other members of the Phyllachorales, which produced either a clypeus or stroma, clustered with Glomerella. Of the taxa examined, was Coccodiella the closest relative of Phyllachora. Magnaporthe was closely related to the Diaporthales. Our 18S rDNA data highly supported Glomerella being accommodated in a separate family
ABSTRACT
Isolados de Colletotrichum gloeosporioides de abacateiros cultivados no Nordeste do Brasil foram estudados em culturas monoconidiais. A maioria dos isolados produziram massas de conídios distribuidas em anéis concêntricos na superfície do BDA em resposta a alternância de luz. Algumas culturas monoconidiais formaram peritécios, porém baixa produçäo de conídios, enquanto que outras produziram conídios em abundância, mas näo formaram peritécios. Em geral, houve produçäo de esclerócios escuros, pequenos e de formato esférico. Os conídios foram produzidos em sucessäo na extremidade de conidióforos fialídicos ou no ápice de setas. Estas, apresentaram-se retas, septadas, escuras, com ápice mais claro e, em alguns casos, férteis. Todos os isolados monoconidiais dentro de uma mesma érea geográfica ou entre elas mostraram variaçäo em relaçäo a tamanho de conídios e apressóriois. A diferença
Subject(s)
Lauraceae/microbiologyABSTRACT
Foram estudados alguns aspectos morfológicos funcionais de apressórios de Colletotrichum gloeosporioides de diferentes fontes e localidades do Nordeste do Brasil. De cada isolado, foram feitas 15 culturas monoconidiais, sendo utilizada a técnica de microcultura para os estudos morfológicos dos apressórios havendo variaçäo no tamanho, forma e quantidade produzida entre os isolados. Um mesmo isolado mostrou apressórios levemente lobados e näo lobados, os quais variaram de castanho escuro a claro, ocasionalmente apresentando um septo, com um poro germinativo a cada célula. Em alguns casos, os apressórios germinaram e formaram apressórios secundários isolados ou em cadeias. Algumas vezes, eles formaram um tubo germinativo que deu origem a conídios de um modo fialídico. Estes resultados sugerem que a importância dos apressórios na natureza, näo é somente a sua capacidade de penetrar diretamente na superfície do hospedeiro, mas também, a sua