Date on Master's Thesis/Doctoral Dissertation

8-2025

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Biology

Degree Program

Biology, PhD

Committee Chair

Perlin, Michael H.

Committee Member

Schultz, David J.

Committee Member

Lackey, Alycia CR

Committee Member

Running, Mark

Committee Member

Klinge, Carolyn M.

Author's Keywords

Fungi; genetics; RNA editing; adenosine deaminase; molecular biology

Abstract

A-to-I RNA editing is a process that occurs post-transcriptionally. Through this process, adenosine (A) is replaced by inosine (I) in RNAs by adenosine deaminase enzymes that act on the single-stranded RNA. These enzymes, also known as ADARs, act on RNA. The translation and splicing mechanisms subsequently interpret inosine as guanosine (G), which effectively alters genetic information. This kind of RNA alteration can cause both nonsynonymous and synonymous changes in codon, which may have an impact on protein function. A group of over 89 basidiomycete fungal species known as the Microbotryum violaceum complex infects a similarly large group of plant host species. Each species in this complex shows significant postzygotic isolation, which is evidence of great genetic differentiation and specialization. Microbotryum superbum (MvSup), M. intermedium (MI), and M. lychnidis-dioicae (MVLG) are members of the M. violaceum fungal complex. Each species infects specific host plant species, resulting in what is commonly known as anther smut. Microbotryum species exhibit a dimorphic life cycle, consisting of a haploid saprophytic yeast-like stage and a dikaryotic plant-parasitic stage. The goal of this study is to understand the role of A to I RNA editing events in the scenario of host pathogen interaction and in terms of evolutionary relationship among the species of the Microbotryum complex. We aimed to characterize the patterns of A-to-I RNA editing across the Microbotryum transcriptome, with focus on different developmental stages of its life cycle. This involved utilizing advanced RNA sequencing and bioinformatical approaches to identify and map the various sites of RNA editing for all fungal transcripts (i.e., here, mRNAs). The potential impacts of these events on gene expression, as well as on transcript stability and protein function, were assessed. By elucidating the effects of these post-transcriptional modifications, I hope to gain insights into the functional relevance of RNA editing in the biology and development of Microbotryum. We have also characterized one of the ADAR-like genes responsible for RNA editing in Microbotryum superbum, by analyzing RNAseq data and gene expression in the heterologous model system, yeast (S. cerevisiae) to understand how they participate in controlling gene expression and fungal growth. The results of this investigation will broaden our understanding of the functional and evolutionary implications of this essential post-transcriptional change in basidiomycete fungi throughout their life cycle, in addition to aiding our understanding of A-to-I RNA editing in Microbotryum. We also characterized another gene in M. superbum that is similar to yeast TAD1. We aimed to determine how the A-to-I editing pattern changes when the TAD1-like gene from Microbotryum superbum is expressed in S. cerevisiae. The results of this investigation will help us understand A-to-I editing in fungi and will provide us with the significance of tRNA and mRNA editing and its putative role in fungal adaptation in different environments. Our findings provide insight into the post-transcriptional modifications in the biology and pathogenicity of this obligate fungal parasite and may also relate to the broader concepts concerning the evolution and functional relevance of a large number of RNA editing events in other pathogenic basidiomycete fungi. Thus, our research should lead to better understanding of how the editing process influences the expression of pathogenicity related genes in these fungi.

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