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The Verrucariaceae (Ascomycota) is a family of mostly lichenized fungi with a unique diversity of algal symbionts, including some algae that are rarely or never associated with other lichens. The phylogenetic position of most of these algae has not yet been studied and, because morphology-based identifications can often be misleading, molecular data is necessary to revisit their identity and to explore patterns of association between fungal and algal partners. For this reason, the diversity of photobionts in this lichen family was investigated using molecular markers (rbcL and nuSSU) amplified from DNA extracts of lichen thalli and cultured isolates. Although a single algal genus, Diplosphaera (Trebouxiophyceae), was associated with 12 out of the 17 sampled genera of Verrucariaceae, representatives of eight other genera in five orders of the Chlorophyta and one genus in the Xanthophyceae also form lichen associations with members of the family. Fungal genera with simple crustose thalli (e.g. Hydropunctaria, Wahlenbergiella, Bagliettoa) use a high diversity and unusual selection of photobionts. In contrast, fungal genera with more complex thalli (e.g. Placidium, Dermatocarpon) tend to have lower photobiont diversity. Habitat requirements and phylogenetic histories are both partly reflected in the observed patterns of associations between lichenized fungi from the family Verrucariaceae and their photobionts. [ABSTRACT FROM AUTHOR]

Controversial data on the pathways and effects of lichen growth on and near bryophytes and vascular plants are reviewed. In most cases, plants which are used as growth substrates positively influence lichen mineral nutrition and are poorly affected by lichen overgrowth, but several reports of negative relationships, including lichen parasitism and allelopathic interferences, prevent generalizations. The allelopathy of terricolous lichens against neighboring plants has been suggested by in vitro investigations, and a multidirectional phytotoxic mode of action has been shown for lichen secondary metabolites. Recent researches on field settings, instead, offer little support of lichen allelopathy, and plant allelopathy against lichens has so far been neglected. A comparison with lichen-rock interactions indicates that a common set of physical and chemical factors can explain the heterogeneous reciprocal effects that exist between lichens and plants, which depend on the species involved, and highlights gaps that need further studies. [ABSTRACT FROM AUTHOR]