Acremoxanthone E, a novel member of heterodimeric polyketides with a bicyclo[3.2.2]nonene ring, produced by Acremonium camptosporum W. GAMS (Clavicipitaceae) endophytic fungus.

Bioactivity-directed fractionation of the organic mycelium extract of the endophytic fungus Acremonium camptosporum W. Gams (Clavicipitaceae), isolated from the leaves of Bursera simaruba (Burseraceae), led to the isolation of six major heterodimeric polyketides, including one not previously characterized acremoxanthone derivative. In addition, the already known acremoxanthone C, acremonidins A and B, and acremoxanthones A and B were obtained. The structure of the new compound was established by extensive NMR studies, including DEPT, COSY, NOESY, HSQC, and HMBC methods. The trivial name proposed for this compound is acremoxanthone E. In addition, the structure of acremoxanthone C was unequivocally established for the first time, through X-ray crystal-structure analysis. The anti-oomycete activities of the pure compounds were tested against four economically important phytopathogenic oomycetes. Inhibitory concentration for 50% diameter growth reduction, IC50 , values for the four phytopathogens ranged from 6 to 38 µM. Also, in parallel, the cytotoxic activities against six cancer cell lines were evaluated showing IC50 values similar to those of cisplatin. To the best of our knowledge, this is the first report on three different groups of heterodimeric polyketides, linked by a bicyclo[3.2.2]nonene, such as xanthoquinodins, acremonidins, and acremoxanthones, which are isolated from an endophytic fungus. In addition, a common biosynthetic origin could be proposed.

Allelochemical effects of volatile compounds and organic extracts from Muscodor yucatanensis, a tropical endophytic fungus from Bursera simaruba.

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.

Naphthoquinone spiroketal with allelochemical activity from the newly discovered endophytic fungus Edenia gomezpompae.

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.

Conidioma development in Ophiodothella vaccinii.

The perithecial ascomycete Ophiodothella vaccinii causes a leafspot disease of sparkleberry (Vaccinium arboreum), in which an anamorph is produced early in the life cycle of the fungus. The anamorph forms shiny, black, pulvinate conidiomata that contain a single central pore. After initial infection, fungal hyphae permeate the interior tissues of the leaf, creating lesions. Conidiomata are initiated by the formation of a small layer of intertwined, thicker-walled hyphae beneath the epidermis of the lesion. Near the center of this hyphal layer a subglobose collection of thick-walled hyphae is formed. This hyphal collection grows upward, becoming conical and pressing against the epidermis. Elongation of a columnar apex of the hyphal collection ruptures the epidermis, creating a pore. Subsequent expansion and development of conidiophores and conidia push the epidermis upward, lifting it away from the column, opening the pore and allowing conidia to emerge. The conidioma is regarded as a modified acervulus.

Poroleprieuria, a new xylariaceous genus from Mexico.

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.

Morphological variability of Colletotrichum gloesporiodes isolates from avocado trees from northeastern Brazil

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

Appressoria of Brazilian isolates of Colletotrichum gloeosporioides (penz.) sacc. causal agent of anthracnoses diseases

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