Phylogenetics of corticolous early incidence Dothideomycetes

Integrating described fungi into their phylogenetic tree of life is far leaping behind the detection of fungi in the environment by modern sequencing techniques in ecological studies. Insertion of the latter organisms that are solely known from ITS sequences and naming them is hampered by the numerous gaps still present in current trees based on molecular phylogeny. The project defined here aims at filling some of the gaps in the phylogeny of the Ascomycota, in particular within the Pleosporales of the Dothideomycetes. As this is a large order, the study is limited to fungi that form fructifications in bark of trees and shrubs early after death of the respective plants. Such fungi are of broad interest, because they may be primary invaders and causal agents of plant death or secondary invaders and saprotrophs. In particular the study is concentrated on the family Pleomassariaceae and the genus Valsaria, where the proposer has already comprehensive data, and the family Cucurbitariaceae, where little is known from a molecular perspective, but where good morphological information is available, still a large number of additional species and a splitting into several genera may be expected. The main activities of the project include therefore an analysis of Cucurbitaria primarily based on teleomorphs on the generic and species level, with respect of biodiversity in Europe, especially on the complex host family Leguminosae, phylogenetic structure, and relationships with anamorphs, which will be assessed by their formation in culture and by sequencing of putative anamorphs associated with teleomorphs on the natural hosts. The taxonomy of the species will be clarified and adapted to the new regulations as defined in the drastically altered new International Code of Nomenclature for algae, fungi, and plants (Melbourne Code, ICN). In addition, the postulate that abundant fructifications on recently dead or partly still living plant parts may indicate endophytic lifestyle will be assessed in this project using model species of Cucurbitaria. Other genera of the Pleosporales, particularly such that are often confounded with Cucurbitaria or which are difficult to define and strongly call for clarifications in order to provide for a better understanding of phylogenetic and evolutionary relationships of pleosporalean fungi, are planned to be included in the study, depending on availability and residual time and work capacity left by the activities defined above. The include genera like Chaetoplea, Cucurbidothis, Fenestella, Karstenula or Teichospora, and those where sequence information has been accumulated recently in the lab of the proposer such as Melanomma, Ohleria, Requienella or Thyridaria. Representative cultures will be preserved in a publicly accessible strain collection for future research in other disciplines. Essential barcoding information will be provided.

In this project 2 new classes, 3 new orders, 8 new families, 15 new genera and 51 new species of Ascomycota were detected and published. This allowed for a consolidation, extension and completion of the phylogenetic tree of Dothideomycetes, particularly within the order Pleosporales, at several ranks. For this, trees and shrubs of agricultural use, in nature and in parks, were studied with regard of occurrence and diversity of certain bark inhabiting members of Dothideomycetes. This is one of the largest classes of sac fungi (Ascomycota) and contains particularly numerous species, which are, in many parts, largely unknown with regard to their phylogenetic relationships and correct names. Using fresh material, mostly collected in Central and mediterranean Europe, pure cultures were produced, DNA preparations of which were used to determine sequences of certain genes in order to infer phylogenetic relationships using certain phylogeny programs. The family Cucurbitariaceae, of which only rudimentary gene sequences of a single species had been available, was studied in detail. An interesting finding was that the majority of species in this family are fungicolous in nature, i.e., that they feed on other fungi. In addition, relationships between sexual and asexual states of these fungi were detected, outside the Cucurbitariaceae particularly also for the mould genus Helminthosporium, where an experimental proof of relationships with sexual (Splanchnonema- and Pleomassaria-like) states or morphs via DNA sequences is entirely new. Such morphs would have been classified in an entirely different family, the Pleomassariaceae. The family Requienellaceae, whose members were regarded as lichens, was found to belong to the Xylariales, an order of non-lichenised fungi. This result is particularly surprising, because fissitunicate bitunicate asci where hitherto virtually unknown in the class Sordariomycetes, which contain the Xylariales. For the genus Valsaria, which forms conspicuous black warts on recently dead branches and whose life cycles feature four asexual stages, the species composition was clarified and a new family in a new order was erected. Particularly important for phylogenetic resolution and species recognition was also the introduction of sequences of protein-coding genes in phylogenetics of several groups of Dothideomycetes, where in many cases only sequences of ribosomal genes of few members had been available. In this regard we point out the use of introns (e.g. of the translation elongation factor 1 alpha), which are less conserved and thus more variable than exons. Pure cultures of all new fungal species were deposited in an international strain collection, where they are available for further research.