Interactions between Psilocybe fasciata and its companion fungus Acremonium strictum

Molecular and morphological characterization of Xylaria karsticola (Ascomycota) isolated from the fruiting body of Macrolepiota procera (Basidiomycota) from Bulgaria

The present study is the first to report Xylaria karsticola isolated from the basidiocarp of Macrolepiota procera (Basidiomycota), from Stara Planina Mountain, Bulgaria and second report for such species found in Europe. The fungal isolate was in vitro cultivated and the morphology was observed. It was primarily determined as a xylariaceous morphotype at the intragenus level, based on the evaluation of colony growth rate, color, and stromatic structure formation and was confirmed by unique conidiophores and conidia. The molecular identification of the isolate was performed by amplification of ITS1-5.8S-ITS2 region and the strain was identified as Xylaria karsticola with 97.57% of confidence. The obtained sequence was deposited in the GenBank database under the accession number MW996752 and in the National Bank of Industrial Microorganisms and Cell Cultures of Bulgaria under accession number NBIMCC 9097. The phylogenetic analysis of the isolate was also conducted by including 26 sequences obtained from different Xylaria isolates. Considering the phylogenetic data, X. karsticola NBIMCC 9097 was grouped along with other X. karsticola isolates, although the DNA sequence of the novel X. karsticola was rather distantly related to the other X. karsticola sequence data. The results were supported by the bootstrap analysis (100%) and indicated the different origin of the examined X. karsticola NBIMCC 9097.

ACTIVIDAD BIOCONTROLADORA IN VITRO DE MACROHONGOS CONTRA DIFERENTES HONGOS FITOPATÓGENOS

Las enfermedades causadas por hongos en las plantas son una gran preocupación en la producción agrícola. Los macromicetos son una fuente potencial de compuestos antifúngicos que podrían usarse para controlar estas enfermedades. El objetivo de este estudio fue evaluar la actividad biocontroladora in vitro de cuatro macromicetos de los géneros Xylaria, Agrocybe, Psilocybe y Stereum sobre diferentes hongos fitopatógenos. Para ello, se determinó la curva de crecimiento de los macrohongos en dos medios: papa dextrosa (PDA) y salvado de trigo (ST) y se caracterizaron las interacciones y la inhibición in vitro de hongos fitopatógenos. Se realizó la extracción y caracterización de metabolitos secundarios de la biomasa, el medio extracelular y del homogeneizado del micelio y caldo en los hongos con mayor porcentaje de inhibición. Finalmente, se evaluó la actividad antifúngica in vitro de estos extractos. Las curvas de crecimiento cambiaron con la fuente de carbono, tres de cuatro macrohongos mostraron una mayor acumulación de biomasa en PDA que en ST. Las interacciones de Xylaria se clasificaron principalmente como reemplazo, obteniendo el mayor nivel de antagonismo en PDADos de los tres extractos evaluados mostraron actividad antifúngica contra los tres patógenos aislados en concentraciones de 18 μg/ml para extractos metanólicos de biomasa y 2,5 % para el filtrado de homogeneizado con inhibiciones de 10 % a 80 %.  La caracterización de los metabolitos de Xylaria mostró como posibles compuestos responsables de la actividad a los ácidos grasos. Este trabajo mostró el potencial de estos hongos para el control de enfermedades fúngicas.

Mycoparasitism of Helminthosporium solani by Acremonium strictum

ABSTRACT Isolates of Helminthosporium solani, the causal agent of silver scurf of potato, collected from multiple locations consistently show white sectoring and rings, differential coloration, and reduced sporulation in culture. It has been accepted that this growth pattern is normal for H. solani cultures. Scanning electron microscopy confirmed the presence of a contaminating fungus in close association with cultures of H. solani. Repeated hyphal tip isolation techniques were used to separate H. solani from the fungal contaminant. Resultant pure cultures of H. solani were uniformly black in color, without white sectors or rings. The contaminating fungus was identified as Acremonium strictum. The purpose of this study was to elucidate the relationship between A. strictum and H. solani, and evaluate the impact of the fungicolous A. strictum on the growth and biology of H. solani. In vitro studies demonstrated that A. strictum significantly reduced sporulation of H. solani isolates from 65 to 35%, spore germination from 53 to 43%, and mycelial growth from 40 to 32% compared with noncontaminated cultures of H. solani. These data indicate that A. strictum is antagonistic to H. solani, and can be considered a mycoparasite. A. strictum reduced H. solani conidia production on minitubers, thereby reducing inoculum for infection. However, treatment with A. strictum does not reduce silver scurf of previously infected tubers. Further studies are warranted to determine the full potential of A. strictum as a biological control agent of H. solanii-incited silver scurf of stored potato tubers and the most effective manner of use.