PHYLOGENY AND BIODIVERSITY OF THE HYPOCREALES AND DIAPORTHALES

Authors: Rossman, Amy; Castlebury, Lisa; Samuels, Gary

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/12/2006
Publication Date: 7/26/2006
Citation: Rossman, A.Y., Castlebury, L.A., Samuels, G.J. 2006. Phylogeny and biodiversity of the Hypocreales and Diaporthales. [Abstract]. 8th International Mycological Congress, Cairns, Australia, Abstracts Book 2, p. 337.

Interpretive Summary:

Technical Abstract: Over the past decade much progress has been made in understanding the phylogeny of the two major pyrenomycete orders, the Hypocreales and Diaporthales. Families have been accurately outlined and genera defined within each order. In both orders some genera and species exist that do not fall into any known family. Are these monotypic lineages or simply representative of unsampled groups? With increased sampling species or genera that were initially considered aberrant have clustered with related species and genera that are now regarded as families. However, discovery of synapomorphies has been difficult as obvious morphological characters are shown not to be phylogenetically informative. Multigene phylogenies combining nuclear ribosomal genes with protein genes are especially useful in resolving these relationships. Both the Hypocreales and Diaporthales are rich in asexual states with some lineages composed almost entirely of asexually reproducing species. Within genera the number of species has increased greatly especially when the asexual states are included as in such well-studied groups as Bionectria-Clonostachys, Calonectria-Cylindrocladium, Hypocrea-Trichoderma and Gnomonia-Discula. In most cases the sexual state is conserved morphologically with the greatest variability expressed in the asexual state. Conscientious collecting has revealed connections between sexual and asexual states suggesting that many supposed exclusively asexual species have rarely produced or cryptic sexual states. Field work combined with sequence data has revealed many previously undescribed species.. In general the more a group is studied the greater the number of species discovered. For most genera among these little sampled microfungi the asymptote of the discovery curve has not yet been reached. In addition sequence data of species complexes reveal the existence of previously unrecognized, morphologically cryptic species. These new species, once freed from the yoke of morphological constraint, sometimes turn out to have useful biological properties not manifested by the oppressor name. These well-defined species of Trichoderma have been shown to be useful such as in the biological control of cacao pathogens. New species and new lineages within phylogenetically complex species are being discovered as endophytes in the trunks of woody tropical crops. This research demonstrates that accurately defining genera and species in such economically significant orders of fungi such as the Diaporthales and Hypocreales is the first step in controlling the diseases they cause or using them in biological control.