Stefano Terracciano

Improved biomonitoring of airborne contaminants by combined use of holm oak leaves and epiphytic moss

Concentrations of 12 elements (Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb and Zn) and 16 EPA-listed PAHs were detected in Quercus ilex leaves and the epiphytic moss Leptodon smithii collected at urban, periurban and extraurban holm oak stands, in two Italian Regions (Campania and Tuscany). Levels of environmental contaminants were generally higher in leaves and moss from urban areas than periurban and extraurban ones and samples from Campania had the highest PAH content. The epiphytic moss accumulated higher concentrations of trace elements than leaves and the latter showed a higher accumulation capability for PAHs, especially for those with low molecular weight. The different bioaccumulation in leaves and moss were explained in terms of their distinctive morphological and ecophysiological characteristics. The combined approach seems a promising tool for the monitoring of a wide range of pollutants in Mediterranean urban and extraurban environments.

Molecular biodiversity in the moss Leptodon smithii (Neckeraceae) in relation to habitat disturbance and fragmentation

Bryophytes seem particularly suitable to investigate genetic diversity in relation to habitat disturbance due to their large employment as bioindicators and to the recent application of molecular markers to moss population studies. Genetic variation and structure were analysed in seven urban, extraurban and remote populations of Leptodon smithii, an epiphytic moss of Quercus ilex, a phanerogamic species of Mediterranean climax vegetation. A total of 210 individual shoots were DNA extracted and amplified with internal simple sequence repeat (ISSR) primers, and 54 haplotypes were identified. An uneven distribution of haplotype number and frequencies was observed among sites, with a higher number of haplotypes and more homogeneous haplotype frequencies in the extraurban/remote populations. Molecular diversity indices were overall higher in the extraurban sites than in the urban ones. Multilocus linkage disequilibrium values were in line with the occurrence of sexual/asexual reproduction in the seven populations. The isolation-by-distance model was not supported by Mantel test among sites; however, within-population fixation index (FST) highlighted a clear relation between genetic and physic distances among trees, suggesting a limited dispersal range for L. smithii’s spores. The genetic structure was mainly affected by population size, wood structure and extent, and genetic drift consequent to habitat fragmentation and human-induced disturbance.

Trace element content and molecular biodiversity in the epiphytic moss Leptodon smithii: Two independent tracers of human disturbance

This paper focuses on chemical composition of the epiphytic moss Leptodon smithii, gathered on Quercus ilex bark, assessed in seven sites located in urban and extra-urban/remote areas of southern Italy, a poorly surveyed geographic area. The concentrations of Cr, Cu, Pb and Zn in moss tissue are generally more abundant in moss gathered in the urban sites; among extra-urban/remote sites Valle delle Ferriere showed the highest metal concentrations, mostly related to an industrial activity occurred in the past. L. smithii chemistry seems influenced by airborne dust locally enhanced by erosion phenomena, long-range transport of pollutants and marine aerosols. Element content in moss is compared with genetic variability of L. smithii estimated in the same sites. Pearsons correlation coefficient between gene diversity and total element load (r=-0.851; p=0.03) suggests that anthropogenic pressure, determining habitat disturbance and fragmentation, leads both to genetic impoverishment consequent to population shrink, and to a higher accumulation in moss tissues, as a consequence of increased airborne major/trace elements. Thus, the coupled evaluation of chemical composition in mosses and gene diversity may prove a useful tool to highlight environmental disturbance in a gradient of land use.

Taxonomy of the Hypnum cupressiforme complex in Italy based on ITS and trnL sequences and ISSR markers

Abstract Bryophytes have sometimes ambiguous morphological diagnostic features, so molecular markers can prove a useful tool in systematics, even more in a well known morphologically variable moss such as Hypnum cupressiforme. This paper focuses on genetic diversity in the H. cupressiforme complex inferred by ISSR markers and ITS and trnL sequences. Shoots from nine Italian populations of H. cupressiforme and from five other species included in the complex were analysed. Sequence divergence among the analysed species is very low, with the exception of Hypnum jutlandicum. The neighbour joining tree based on ISSR data shows that all the H. cupressiforme samples do not merge into a distinct cluster, but spread on the whole dendrogram. Molecular variance is partitioned more within- than between-species. Therefore, the genetic variation detected by ISSR at intra- and inter-specific level appears to be, to a large extent, the result of the individual variation, suggesting that the polymorphism detected appears poorly informative at a taxonomic level. Our results suggest that morphological variation of the H. cupressiforme complex does not always correspond to genetic diversity, and highlight a major molecular divergence of H. jutlandicum within the complex.

Molecular markers based on PCR methods: a guideline for mosses

Abstract In recent years, the number of studies concerning population genetics and phylogenetics in mosses using molecular markers has remarkably grown. This review summarizes the main features of the most used molecular techniques based on PCR and their application in bryology, with particular attention to mosses. This work also provides a bibliographic guide to 108 molecular studies focused on mosses to assist in choosing the most suitable markers according to the main aims of a specific research.

A further tessera in the two-centuries-old debate on the Hypnum cupressiforme complex (Hypnaceae, Bryopsida)

Taxonomic arrangement of Hypnum species has been controversial since the beginning of the nineteenth century. The molecular pattern and phylogenetic relationships within the Hypnum cupressiforme complex, in relation to other pleurocarps species, were investigated by study of nuclear ribosomal ITS1/ITS2 and chloroplast trnLUAA intron sequences. Seven Hypnum species from different continents were sequenced and analysed, with a relatively large set of pleurocarpous mosses. Sequences indicate a low level of genetic differentiation within the complex. Both maximum parsimony and maximum likelihood analyses indicate that Hypnum s.l. is distributed in several clades of pleurocarps; in addition, H. cupressiforme sensu strictu, and the complex, are not monophyletic. Our results clearly circumscribe only two species, H. jutlandicum and H. imponens; phylogenetic analyses, in particular, highlight the isolation of the latter from the complex. Genetic lineages with a clear geographic structure were found in Eurasia; these probably originated during the last glaciations. The presence of H. cupressiforme in some related clades flanking the other species examined supports the occurrence of an ongoing speciation within the complex.

Persistent pollutants and the patchiness of urban green areas as drivers of genetic richness in the epiphytic moss Leptodon smithii.

We determined genetic variation and metal and polycyclic aromatic hydrocarbon concentrations in Leptodon smithii moss collected in holm oak stands at cities, outskirts and remote areas of Campania and Tuscany (Italy) to investigate if anthropogenic pressure (pollutant emissions and land use change) affects moss genetic richness. In both regions, metal and polycyclic aromatic hydrocarbon concentrations reflected the trend urban>outskirts>remote areas, excepting Tuscany remote site. In both regions, the moss gene diversity increased from urban to remote areas. The findings suggest the extent and the fragmentation of urban green areas, as drivers of moss genetic richness.