Phylogenetic analyses of the fungi based on large rDNA data sets

Coevolution of roots and mycorrhizas of land plants

Here, the coevolution of mycorrhizal fungi and roots is assessed in the light of evidence now available, from palaeobotanical and morphological studies and the analysis of DNA-based phylogenies. The first bryophyte-like land plants, in the early Devonian (400 million years ago), had endophytic associations resembling vesicular-arbuscular mycorrhizas (VAM) even before roots evolved. Mycorrhizal evolution would have progressed from endophytic hyphae towards balanced associations where partners were interdependent due to the exchange of limiting energy and nutrient resources. Most mycorrhizas are mutualistic, but in some cases the trend for increasing plant control of fungi culminates in the exploitative mycorrhizas of achlorophyllous, mycoheterotrophic plants. Ectomycorrhizal, ericoid and orchid mycorrhizas, as well as nonmycorrhizal roots, evolved during the period of rapid angiosperm radiation in the Cretaceous. It is hypothesised that roots gradually evolved from rhizomes to provide more suitable habitats for mycorrhizal fungi and provide plants with complex branching and leaves with water and nutrients. Selection pressures have caused the morphological divergence of roots with different types of mycorrizas. Root cortex thickness and exodermis suberization are greatest in obllgately mycorrhizal plants, while nonmycorrhizal plants tend to have fine roots, with more roots hairs and relatively advanced chemical defences. Major coevolutionary trends and the relative success of plants with different root types are discussed. Contents Summary 275 I. Introduction 276 II. Mycorrhizal Fungi 276 III. The Dawn of Mycorrhizas 279 IV. Mycorrhizal Associations of Living and Extinct Plants 282 V. Evolution of Roots 288 VI. The Root as a Habitat for Fungi 290 VII. Mycorrhizal Evolution Trends 295 Acknowledgements 298 References 298.

A comparison of ITS and LSU nrDNA phylogenies of Fulgensia (Teloschistaceae, Lecanorales), a genus of lichenised ascomycetes

The phylogeny of the lichen genus Fulgensia Massal. & De Not. (Teloschistaceae, Lecanorales) is analysed using maximum parsimony and neighbor joining analyses of nuclear ITS and partial large subunit nuclear ribosomal DNA (nrDNA) sequences. Three matrices were analysed with maximum parsimony; an internal transcribed spacer nrDNA matrix, a large subunit nrDNA matrix, and a combined data set. The internal transcribed spacer region contributes 70% of the informative sites to the combined data set. The topology of the trees resulting from the analysis of the internal transcribed spacer region is identical to the tree topology resulting from the combined analysis, but it shows less resolution at basal parts of the tree. Two sites for putative spliceosomal introns in the large subunit nrDNA, at position 808 and 914 (relative to Saccharomyces cerevisiae) are reported. Fulgensia, as currently understood, is polyphyletic and some species have to be excluded. The molecular analyses identified groups of species within the genus that are also supported by anatomical and morphological characters. The results of the analyses are compared with existing classification concepts based on morphological and anatomical data.Key words: LSU, ITS, nrDNA, introns, Fulgensia, phylogeny.