Exploring diploid potato varieties and novel gene-silencing approaches for improved tuber quality

Navarro, Thomas Emilio Guillaume (2025) Exploring diploid potato varieties and novel gene-silencing approaches for improved tuber quality. Doctoral thesis, University of East Anglia.

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Abstract

Genetic approaches to improve the nutritional and post-harvest quality of potato (Solanum tuberosum) are of great interest. Priorities include increasing resistant starch (RS) for health benefits, and decreasing enzymatic browning and cold-induced sweetening, which deteriorate post-harvest quality. The gene targets required to achieve these improvements are known, including Starch Branching Enzymes (SBE), Polyphenol Oxidases (PPO), and Vacuolar Invertase (vINV). However, commercial potato varieties are tetraploid and highly heterozygous, complicating genetic improvement. Inbred diploid lines for hybrid breeding is emerging a promising alternative and are suited to gene editing since transgenes required for editing can be crossed out. In parallel, arising technologies such as Gene-Editing induced Gene-Silencing (GEiGS®) could provide tuber-specific silencing of genes through the editing of endogenous tuber-specific miRNAs, rather than through traditional transgenic RNAi constructs.

In this project, I present a GEiGS®-based strategy for improving tuber quality in diploid potato. I first characterised starch and tuber formation in two inbred diploid lines from the Solynta breeding program, B26 and B100, and their hybrids YD2 and YD3. The lines showed variability in their tuber yield and flower/berry formation. B26 had novel starch granule morphology and increased RS levels. I then generated an RNA-Seq and small RNA-Seq dataset in B26 tubers during development and cold storage, to understand expression patterns of genes involved in starch metabolism. I discovered tuber-specific miRNAs that were active throughout tuber development, as well as during cold storage. Finally, these miRNAs were used to design GEiGS solutions against the target genes, SBE, PPO and vINV. Effectiveness of my GEiGS solutions in silencing SBE1 was confirmed by developing a transient expression assay in Nicotiana benthamiana. I generated stable transformants in diploid potato expressing the GEiGS® solutions to test their function in planta. My work provides the first steps towards improving tuber quality in diploid breeding programs.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Chris White
Date Deposited:	18 Jun 2026 08:03
Last Modified:	18 Jun 2026 08:03
URI:	https://ueaeprints.uea.ac.uk/id/eprint/103425
DOI:

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