Understanding the role of microRNAs in wheat spike development

Carpenter, Sophie J. (2024) Understanding the role of microRNAs in wheat spike development. Doctoral thesis, University of East Anglia.

Preview	PDF Download (8MB) | Preview
	Microsoft Excel Download (439kB)

Abstract

The role of microRNAs, small RNA molecules which repress target genes, in the development of the wheat spike remains largely unknown. In this thesis, I have broadened and deepened our understanding of miRNA functions during early wheat spike development, a period when several yield-determining traits, such as spikelet number, are established.

Using a smallRNA-Seq timecourse, I have generated a comprehensive database of miRNAs that are expressed during early wheat spike development and their putative target transcripts. Using this dataset, I have identified natural and induced variation in miRNA binding sites; a large proportion of these SNPs likely confer dominant, gain-of-function mutations which are promising candidates for integration into breeding pipelines. I have found that natural miRNA binding site variation in the A. E. Watkins landrace collection is significantly associated with changes in spike phenotypes.

Additionally, I have shown how this dataset can be used alongside techniques such as spatial transcriptomics and luciferase assays to deepen our understanding of specific regulatory networks involving miRNAs. I have interrogated the miR172-AP2 interaction in detail and found that almost identical miR172 family members have divergent expression profiles during wheat spike development, exemplifying the importance of characterising closely-related miRNAs independently. However, I have also shown that miR172 family members likely repress the closely related AP2-2 and AP2-5 genes with equivalent efficiency.

The functions of and interactions between VRT-A2, AP2-5, and miR172 appear to be mostly conserved between Arabidopsis and wheat. However, increases in AP2-2 mRNA levels over time and decreases in response to increased and extended VRT-A2 expression cannot be explained by current data. I have generated hypotheses to explain these unexpected observations and proposed experiments to test them. I have used our findings to create a model explaining how VRT-A2, miR172, and AP2-like genes work together to form a complete and fertile wheat spike.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Chris White
Date Deposited:	07 Jul 2025 13:44
Last Modified:	07 Jul 2025 13:44
URI:	https://ueaeprints.uea.ac.uk/id/eprint/99853
DOI:

Downloads

Actions (login required)

View Item