Screening culture filtrates of fungi for activity against Tylenchulus semipenetrans

Culture filtrates of 20 fungi isolated from citrus soils were screened for their activity against Tylenchulus semipenetrans in both in vitro and greenhouse tests. The filtrates of Talaromyces cyanescens (isolates 2-4 and 2-5), Paecilomyces lilacinus, Chaetomium robustum, Acremonium strictum, Engyodontium album, Myrothecium verrucaria, Emericella rugulosa, and Tarracomyces gigaspora consistently inhibited the motility of second-stage juveniles at various concentrations of the filtrate. Dose-response models were used to determine the filtrate concentration required to inhibit the motility of 50% of the juveniles (CI50). The culture filtrate of P. lilacinus showed the highest activity with a CI50 value of 58% that differed from that of C. robustum (CI50 = 68%), and A. strictum CI50 = 82%. The culture filtrates of P. lilacinus, E. album, and T. cyanescens 2-5 maintained their activity when autoclaved at 120ºC for 20 min. The autoclaved filtrate of T. cyanescens 2-4 was more effective at inhibiting juvenile motility (CI50 = 28%) than that of T. cyanescens 2-5 (CI50 = 80%), C. robustum (CI50 = 72 %) and P. lilacinus (CI50 = 72%). The culture filtrate of T. cyanescens 2-4 also inhibited egg hatching. Nematode reproduction on Cleopatra mandarin and Carrizo citrange were respectively reduced by the culture filtrate of P. lilacinus and the autoclaved filtrate of T. cyanescens 2-4. These results support the hypothesis that soil fungi may contribute to regulate nematode densities by the production of secondary metabolites with nematicidal activity.Se evaluó la actividad de filtrados de cultivos de 20 hongos aislados del suelo en parcelas de cítricos frente a Tylenchulus semipenetrans mediante ensayos in vitro y en invernadero. Los filtrados de Talaromyces cyanescens (aislados 2-4 y 2-5), Paecilomyces lilacinus, Chaetomium robustum, Acremonium strictum, Engyodontium album, Myrothecium verrucaria, Emericella rugulosa, y Tarracomyces gigaspora inhibieron consistentemente la movilidad de los juveniles de segundo estadio del nematodo a varias concentraciones del filtrado. Se utilizaron modelos de dosis-respuesta para determinar la concentración del filtrado que inhibía la movilidad del 50% de los juveniles (CI50). El filtrado del cultivo de P. lilacinus mostró la máxima actividad entre todos los ensayados con un valor de CI50 del 58%, la cual era superior a la de los filtrados de C. robustum (CI50 = 68%) y A. strictum (CI50 = 82%). Los filtrados de P. lilacinus, E. album, y T. cyanescens 2-5 retenían su actividad después de autoclavarlos a 120ºC durante 20 min. La inhibición de la movilidad de los juveniles obtenida con el filtrado autoclavado de T. cyanescens 2-4 (CI50 = 28%) fue superior a la de los filtrados de T. cyanescens 2-5 (CI50 = 80%), C. robustum (CI50 = 72%), ó P. lilacinus (CI50 = 72%). El filtrado de T. cyanescens 2-4 también inhibió la eclosión de los huevos del nematodo. La reproducción del nematodo en mandarino Cleopatra y citrange Carrizo fue menor cuando los juveniles se incubaron en el filtrado de P. lilacinus y en el filtrado autoclavado T. cyanescens 2-4, respectivamente. Estos resultados apoyan la hipótesis de que los hongos del suelo pueden contribuir a la regulación de las poblacionales de los nematodos mediante la producción de metabolitos secundarios con acción nematicida

New Coelomycetous Fungi from Freshwater in Spain

Coelomycetous fungi are ubiquitous in soil, sewage, and sea- and freshwater environments. However, freshwater coelomycetous fungi have been very rarely reported in the literature. Knowledge of coelomycetous fungi in freshwater habitats in Spain is poor. The incubation of plant debris, from freshwater in various places in Spain into wet chambers, allowed us to detect and isolate in pure culture several pycnidia-producing fungi. Fungal strains were phenotypically characterized, and a phylogenetic study was carried out based on the analysis of concatenated nucleotide sequences of the D1–D2 domains of the 28S nrRNA gene (LSU), the internal transcribed spacer region (ITS) of the nrDNA, and fragments of the RNA polymerase II subunit 2 (rpb2) and beta tubulin (tub2) genes. As a result of these, we report the finding of two novel species of Neocucurbitaria, three of Neopyrenochaeta, and one of Pyrenochaetopsis. Based on the phylogenetic study, we also transferred Neocucurbitaria prunicola to the genus Allocucurbitaria. This work makes an important contribution to the knowledge of the mycobiota of plant debris in freshwater habitats

Novel Freshwater Ascomycetes from Spain

Freshwater ascomycetes are a group of fungi of great ecological importance because they are involved in decomposition processes and the recycling of organic matter in aquatic ecosystems. The taxonomy of these fungi is complex, with representatives in several orders of the phylum Ascomycota. In the present study, we collected ninety-two samples of plant debris submerged in freshwater in different locations in Spain. The plant specimens were placed in wet chambers and developed several fungi that were later isolated in pure culture. A main phylogenetic tree using the nucleotide sequences of D1–D2 domains of the 28S nrRNA gene (LSU) was built to show the taxonomic placement of all our fungal strains, and, later, individual phylogenies for the different families were built using single or concatenated nucleotide sequences of the most suitable molecular markers. As a result, we found a new species of Amniculicola that produces a coelomycetous asexual state, a new species of Elongatopedicellata that produces an asexual state, a new species of Neovaginatispora that forms both sexual and asexual states in vitro, and the sexual states of two species of Pyrenochaetopsis, none of which have been reported before for these genera. In addition, we describe a new species of Pilidium characterized by the production of copper-colored globose conidiomata, and of Pseudosigmoidea, which produces well-developed conidiophores

New Dothideomycetes from Freshwater Habitats in Spain

The Dothideomycetes are a class of cosmopolitan fungi that are present principally in terrestrial environments, but which have also been found in freshwater and marine habitats. In the present study, more than a hundred samples of plant debris were collected from various freshwater locations in Spain. Its incubation in wet chambers allowed us to detect and to isolate in pure culture numerous fungi producing asexual reproductive fruiting bodies (conidiomata). Thanks to a morphological comparison and to a phylogenetic analysis that combined the internal transcribed spacer (ITS) region of the nrDNA with fragments of the RNA polymerase II subunit 2 (rpb2), beta tubulin (tub2), and the translation elongation factor 1-alpha (tef-1) genes, six of those strains were identified as new species to science. Three belong to the family Didymellaceae: Didymella brevipilosa, Heterophoma polypusiformis and Paraboeremia clausa; and three belong to the family Phaeosphaeriaceae:Paraphoma aquatica, Phaeosphaeria fructigena and Xenophoma microspora. The finding of these new taxa significantly increases the number of the coelomycetous fungi that have been described from freshwater habitats

Evaluación de la actividad antagonista de filtrados de hongos frente al nematodo de los cítricos Tylenchulus semipenetrans

Peer Reviewe

Evaluación de la actividad antagonista de filtrados de hongos frente al nematodo de los cítricos Tylenchulus semipenetrans

Peer Reviewe

Evaluación de la actividad antagonista de filtrados de hongos frente al nematodo de los cítricos Tylenchulus semipenetrans

Peer Reviewe