Differential thermotolerance adaptation between species of coccidioides

Heather L. Mead, Paris S. Hamm, Isaac N. Shaffer, Marcus de Melo Teixeira, Christopher S. Wendel, Nathan P. Wiederhold, George R. Thompson, Raquel Muñiz-Salazar, Laura Rosio Castañón-Olivares, Paul Keim, Carmel Plude, Joel Terriquez, John N. Galgiani, Marc J. Orbach, Bridget M. Barker

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Coccidioidomycosis, or Valley fever, is caused by two species of dimorphic fungi. Based on molecular phylogenetic evidence, the genus Coccidioides contains two reciprocally monophyletic species: C. immitis and C. posadasii. However, phenotypic variation between species has not been deeply investigated. We therefore explored differences in growth rate under various conditions. A collection of 39 C. posadasii and 46 C. immitis isolates, representing the full geographical range of the two species, was screened for mycelial growth rate at 37C and 28C on solid media. The radial growth rate was measured for 16 days on yeast extract agar. A linear mixed effect model was used to compare the growth rate of C. posadasii and C. immitis at 37C and 28C, respectively. C. posadasii grew significantly faster at 37C, when compared to C. immitis; whereas both species had similar growth rates at 28C. These results indicate thermotolerance differs between these two species. As the ecological niche has not been well-described for Coccidioides spp., and disease variability between species has not been shown, the evolutionary pressure underlying the adaptation is unclear. However, this research reveals the first significant phenotypic difference between the two species that directly applies to ecological research.

Original languageEnglish (US)
Article number366
Pages (from-to)1-14
Number of pages14
JournalJournal of Fungi
Volume6
Issue number4
DOIs
StatePublished - Dec 2020

Keywords

  • Coccidioidomycosis
  • Fungal pathogen
  • Growth rate
  • Phenotypic variation
  • Valley fever

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Plant Science
  • Microbiology (medical)

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