Biology ETDs

Publication Date

Spring 3-25-2019

Abstract

Advances in DNA sequencing and data analysis make it possible to address questions in population genetics and evolution at the genomic level. Fungi are excellent subjects for such studies, because they are found in diverse environments, have short generation times, can be maintained in culture and have relatively small genomes. My research employed genetic approaches using a variety of sequencing technologies and methods of analysis to explore questions in fungal evolution.

In one study, I explored the genetics behind differences in thermotolerance between isolates of Neurospora discreta from Alaska and New Mexico. Isolates from the two states exhibited differences in maximal growth temperature, with New Mexico isolates being substantially more thermotolerant than isolates from Alaska. Genomic scale comparisons of progeny from crosses between isolates from New Mexico and Alaska indicated that two regions, one on chromosome III and another on chromosome I, are responsible for differences in thermotolerance. Examination of these regions revealed numerous differences between the New Mexico and Alaska isolates at nucleotide and amino-acid levels; and it identified candidate genes for being important for differences in maximal growth temperatures.

In a second study, I explored the genomic differences between pathogenic and endophytic isolates in the genus Monosporascus. Culture and sequence-based surveys of root associating fungi at the Sevilleta National Wildlife Refuge (SNWR) revealed the ubiquitous presence of members of this genus. Although M. cannonballus is known as a severe pathogen of melon roots in agricultural settings, all of the host plants associating with Monosporascus species in natural settings appeared to be disease free. Complete genome sequences were obtained from three M. cannonballus isolates, an M. ibericus isolate and six SNWR isolates. Comparative genome analyses revealed that 1) isolates of Monosporascus possess genomes that are more than twice the size of those typical for members of the Sordariomycetes, while having typical numbers of protein-coding genes; 2) isolates from diverse grasses, tree and forbs include lineages closely-related to previously described species including M. cannonballus, in addition to novel lineages; and 3) species of Monosporascus and other Xylariales lack mating-type gene regions typical of other members of the Pezizomycotina.

Language

English

Keywords

Fungal, Genomics, Neurospora, Monosporascus, Xylariales

Document Type

Dissertation

Degree Name

Biology

Level of Degree

Doctoral

Department Name

UNM Biology Department

First Committee Member (Chair)

Donald O. Natvig

Second Committee Member

Donald Lee Taylor

Third Committee Member

Scott L. Collins

Fourth Committee Member

Jason Stajich

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