Alex Smith MS Thesis Defense

Department of Integrative Biology
Graduate Thesis Defense

Alex Smith photo


CONGRATULATIONS to Alex Smith who successfully defended his MS Thesis on April 10th!  Alex is a MS student in Dr. Sarah Branco's lab and intends to pursue a career in mycoindustry after graduation!


Alex Smith

Master’s Degree Candidate
Dr. Sarah Branco’s Lab
CU Denver Department of Integrative Biology

When: April 10, 2023
Where: Zoom at 3:15pm (MST)
Please email Jacki Craig ( for the Zoom Link

Uncovering the Transcriptomic Profile of Zinc Tolerance in Suillus luteus

Due to the increase of anthropogenic waste, Zinc has become a major contaminant in soil environments. Even though high zinc environments can disrupt the growth, survival, and reproduction of biota, some fungal species display zinc tolerance. Previous research found that cell processes such as metal transport and immobilization and oxidative stress relief contribute to zinc tolerance, however the genes and mechanisms underlying fungal zinc tolerance remain unexplored. To fill this gap in knowledge, we investigated the gene expression profile of zinc tolerance in the fungal species Suillus luteus, a widespread ectomycorrhizal fungus that associates with pine trees and an important pioneer species commonly found in zinc-contaminated sites. We conducted a differential gene expression analysis with zinc-tolerant and -sensitive S. luteus individuals grown on control and zinc-amended media. We found that tolerant and sensitive isolates displayed vastly different patterns of gene expression, with tolerant isolates showing much more transcriptomic variation, while zinc treatment imprinted few transcriptomic changes. Additionally, predicted functions of highly differentially expressed genes included metal transport and chelation, cell signaling, and oxidoreductase activity. Our results suggest that zinc tolerance in S. luteus is largely a constitutively active trait and that cellular mechanisms of tolerance include the exclusion and immobilization of zinc as well as a more efficient recognition and mitigation of metal-induced oxidative stress. Collectively, this study helps better define the mechanisms of Zn tolerance in the ectomycorrhizal fungus S. luteus.