A new measurement tool to consider for airborne pollutants evaluations using lichens.

An important factor affecting acquisition of pollution elements could be the lichen growth form. The Brunauer-Emmett-Teller theory approach has been used to determinate the specific area surface (BET-area) of solids by gas multilayer adsorption. Taking this standard method as a new tool, we measure the specific thallus area in foliose and fruticose lichens to evaluated area/volume relation for bioaccumulation prospects. Some preliminary results of elemental contents such as REEs (La, Sc, Sr) and pollutants (Cd, Co, Pb) were also measured to support the importance to use for the analysis of these thallus attributes.

Potential biocontrol actinobacteria: Rhizospheric isolates from the Argentine Pampas lowlands legumes.

Control of fungal plant diseases by using naturally occurring non-pathogenic microorganisms represents a promising approach to biocontrol agents. This study reports the isolation, characterization, and fungal antagonistic activity of actinobacteria from forage soils in the Flooding Pampa, Argentina. A total of 32 saprophytic strains of actinobacteria were obtained by different isolation methods from rhizospheric soil of Lotus tenuis growing in the Salado River Basin. Based on physiological traits, eight isolates were selected for their biocontrol-related activities such as production of lytic extracellular enzymes, siderophores, hydrogen cyanide (HCN), and antagonistic activity against Cercospora sojina, Macrophomia phaseolina, Phomopsis sp., Fusarium oxysporum, and Fusarium verticilloides. These actinobacteria strains were characterized morphologically, physiologically, and identified by using molecular techniques. The characterization of biocontrol-related activities in vitro showed positive results for exoprotease, phospholipase, fungal growth inhibition, and siderophore production. However, none of the strains was positive for the production of hydrogen cyanide (HCN). Streptomyces sp. MM140 presented the highest index for biocontrol, and appear to be promising pathogenic fungi biocontrol agents. These results show the potential capacity of actinobacteria isolated from forage soils in the Argentine Pampas lowlands as promising biocontrol agents, and their future agronomic applications.

Evolution of complex symbiotic relationships in a morphologically derived family of lichen-forming fungi.

We studied the evolutionary history of the Parmeliaceae (Lecanoromycetes, Ascomycota), one of the largest families of lichen-forming fungi with complex and variable morphologies, also including several lichenicolous fungi. We assembled a six-locus data set including nuclear, mitochondrial and low-copy protein-coding genes from 293 operational taxonomic units (OTUs). The lichenicolous lifestyle originated independently three times in lichenized ancestors within Parmeliaceae, and a new generic name is introduced for one of these fungi. In all cases, the independent origins occurred c. 24 million yr ago. Further, we show that the Paleocene, Eocene and Oligocene were key periods when diversification of major lineages within Parmeliaceae occurred, with subsequent radiations occurring primarily during the Oligocene and Miocene. Our phylogenetic hypothesis supports the independent origin of lichenicolous fungi associated with climatic shifts at the Oligocene-Miocene boundary. Moreover, diversification bursts at different times may be crucial factors driving the diversification of Parmeliaceae. Additionally, our study provides novel insight into evolutionary relationships in this large and diverse family of lichen-forming ascomycetes.

Occurrence of arbuscular mycorrhizas and dark septate endophytes in pteridophytes from a Patagonian rainforest, Argentina.

Arbuscular mycorrhizas (AM) are one of the most widespread types of symbiotic associations. Pteridophytes occupy an important position in the evolution of vascular plants. However, their mycorrhizal state remains poorly understood. The aim of this work was to describe the general mycorrhizal status and the occurrence of dark septate endophytes (DSE) in the pteridophytic flora of a Valdivian temperate forest in Patagonia, Argentina. First, the roots of nine terrestrial species representing six families were examined, and this information was then compared with other surveys concerning the occurrence of AM in other pteridophytic species within the same Valdivian temperate forest. AM were recorded in 98.6% of the samples analyzed in this work and all of them corresponded to the Paris-type morphology. DSEs were also present within the roots of all terrestrial species. A comparison to published results in other ferns and lycophytes that have been studied in this Valdivian temperate forest (161 sporophytes, 21 species and 10 families) was made. Clear differences in colonization patterns between eusporangiate/leptosporangiate and epiphytic/terrestrial species became evident and are discussed.

Chaenothecopsis quintralis, a new species of calicioid fungus.

Chaenothecopsis quintralis from southwestern Argentina is described and illustrated as a new species in the family Mycocaliciaceae. It has been found in three localities in the Andean Patagonian temperate forests, growing strictly on dung of an endemic marsupial Dromiciops gliroides. The new species is distinguished by the hemispherical, black capitulum of ascoma, the presence of asci with croziers, one-celled brown ascospores, and its fimicolous habitat. Analysis of partial nuclear large subunit rDNA (LSU) sequences showed that this taxon is within Mycocaliciales.