ECTOMYCORRHIZAL HOST-SPECIFICITY AND HOST SWITCHING
Ectomycorrhizal host specificity is generally broad, with the majority of species able to associate with a phylogenetically diverse set of host trees. In contrast, fungi in the genus Suillus exhibit highly restricted host ranges, specializing on trees in the family Pineaceae. A single species of Suillus fungi, S. subaureus, has long been cited as a possible exception to the well-established association between Suillus fungi and the Pineaceae. Fruitbody collection records of S. subaureus often include a site description that recognizes the absence of known Suillus hosts and the presence of angiosperm trees such as Quercus and Populous. This project is advised by Dr. Peter Kennedy at the Kennedy Microbe lab and investigates the mechanistic and ecological factors influencing host-range, host-specificity and host-switching in ectomycorrhizal fungi, using S. subaureus as a model.
Fusarium before agriculture:
the evolutionary role of Mycotoxins in native grasses
Fusarium graminearum, the causative agent of Fusarium Head Blight (FHB), is a devastating and widespread fungal pathogen of cereal crops. FHB infection causes severe reductions in both grain yield and grain quality, contaminating seed by producing a family of mycotoxins known as trichothecenes. Despite the significant impact that F. graminearum has on small grain production, the evolutionary history, ecology and chemotypic distribution of F. graminearum outside of agricultural settings is largely unknown. Fusarium spp. producing B-type trichothecenes are thought to have evolved in North America in the middle Pliocene, approximately 3.5 MYA (O’Donnell et al., 2013). As such, grasses native to the United States grain belt have likely had a longer evolutionary history with F. graminearum than cultivated members of the Poaceae which were only introduced to North America by more recent human activity (Michels, 1912; Smith, 1989). Although Fusarium is easily isolated from the seed of native grass species, many native grasses fail to present the suite of symptoms typically associated with trichothecene accumulation in cultivated grasses. This project investigates the chemotypic distribution, possible evolutionary drivers and ecological consequences of Fusarium infection in native perennial prairie grasses growing in the United States' grain belt. This research is being carried out with Dr. H. Corby Kistler in conjunction with the Kistler Lab of Fungal Genetics at the USDA Cereal Disease Laboratory.