Abstract Detail

Mycological Section

Kijpornyongpan, Teeratas [1], Grigoriev, Igor [2], Mondo, Stephen [2], Barry, Kerrie [2], Spatafora, Joseph W. [3], Aime, M. Catherine [1].

Exploring patterns of smut fungi evolution through phylogenomics.

Smut fungi are a heterogeneous group of phytopathogens, most of which belong in Ustilaginomycotina. Smut fungi cause disease on various, usually graminicolous, hosts including several important economic crops such as corn, wheat and sugarcane. Most smut fungi undergo a dimorphic life cycle and some, especially the corn smut fungi (Ustilago maydis), serve as model organisms for genetics and pathogenesis studies. Phylogenetic analyses have shown that, in addition to smut fungi, Ustilaginomycotina also contains non-smut taxa such as animal pathogens and yeast species for which a pathogenic stage is not known. Currently, Ustilaginomycotina comprises ca. 1700 species belonging to 11 orders and four classes. However, ordinal-level relationships for this group are unresolved. Through the 1000 Fungal Genome Project we have generated whole genome shotgun sequences for eight Ustilaginomycotina species selected to represent various trophic strategies across seven orders for which no prior genomic data are available. A phylogenomic pipeline was designed for orthology assessment, sequence alignment and phylogenetic tree reconstruction. Starting from a subset of 246 single-copy orthologs from the Fungal Phylogenomic Database (FunyBASE), the final 96 protein models were used for species tree reconstruction using three different methods: maximum-likelihood, Bayesian inference and pseudo-likelihood. The resolved tree was then used to test hypotheses regarding the origin and evolution of certain traits within Ustilaginomycotina. For example, pathogenicity genes studied in U. maydis appear to be limited to Ustilaginales, suggesting a derived mechanism for host-specific infection. Two mating-type loci were detected in all studied taxa, but they have much variation in terms of placement in the genome, synteny conservation and encoded protein sequences. These and other results will be presented and discussed.

1 - Purdue University, Botany & Plant Pathology, 915 W. State Street, Botany & Plant Pathology, West Lafayette, IN, 47907, USA
2 - DOE Joint Genome Institute, 2800 Mitchell Drive, Walnut Creek, California, 94598, USA
3 - Oregon State University, Botany and Plant Pathology, 2082 Cordley Hall, Corvallis, Oregon, 97331-2902, USA

Keywords:
Ustilaginomycotina
Mating-type loci
Pathogenicity
Evolutionary histories.

Presentation Type: Oral Paper:Papers for Sections
Session: 56
Location: Salon 1/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 8:00 AM
Number: 56001
Abstract ID:266
Candidate for Awards:MSA Best Oral Presentation Award by a Graduate Student