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Li, Janet Xin

University of British Columbia

Beauveria bassiana is an entomopathogenic fungus used as a biological control agent against insect pests related to agriculture, forestry and human health. There is a large amount of phenotypic and genomic variation within the species complex, and characterizing this variation is required to identify the optimal strain for protection against a specific pest. This thesis outlines comparative genomic and transcriptomic analyses of eight B. bassiana isolates, including six wild-type and two UV resistant derivatives to identify the genetic basis of virulence and UV resistance. The five strains demonstrating the highest virulence levels against mountain pine beetle produced high levels of the red pigment, oosporein. Phylogenetic analysis placed the eight strains in two distinct clusters that reflected their morphology, grouping red strains separately from the non-red strains. Genes unique to the red strains included several membrane transporters, transcription factors and toxins, and may confer virulence or other unique biological functions to these strains. Significant differential expression was identified between the red and non-red strains, and these differentially expressed genes likely contribute to increased virulence, transmembrane transport and stress response in the red strains. Several genes encoding toxins, lipases and chitinases were differentially expressed, all of which are crucial to the infection process. Variant calling and differential expression in the UVR derivatives identified several genes of interest involved in oxidoreductase activity, stress response, copper metabolism and DNA replication/repair. These are all important mechanisms for protecting cells from UV-induced damage such as free radicals. Finally, differential correlation analysis identified several transcription factors that may be involved in the regulation of the oosporein biosynthetic gene cluster. The results of this work have narrowed the scope for selecting and/or engineering the most effective strain of Beauveria bassiana for the biological control of insect pests.

Text

2022-07-11

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/82112

Bioinformatics

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/