Genetic and molecular analysis of Solanum disease resistance genes

Heal, Robert Peter James (2024) Genetic and molecular analysis of Solanum disease resistance genes. Doctoral thesis, University of East Anglia.

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Abstract

Plants encode intracellular nucleotide-binding leucine-rich repeat (NLR) receptors which recognise pathogen effectors and trigger an immune response. In this thesis, NLR-mediated immunity is investigated in several contexts, namely, resistance to phloem-limited pathogens, non-host resistance, and the ability of the same NLRs to recognise multiple pathogens.

In Chapter 3, a resistance gene against potato leafroll virus (PLRV) was cloned. This gene, Rladg, encodes a Bs4-like TIR-NLR that recognises a serine protease which is essential for viral replication. Rladg is the first NLR that has been found to confer resistance to a phloem-limited pathogen. PLRV belongs to the Polerovirus genus, which contains many economically important viruses that cause significant yield losses in various crop species. We found that Rladg is capable of broad-spectrum recognition of poleroviruses and explored its potential to elevate resistance to these viruses.

In Chapter 4, the basis of non-host resistance to Phytophthora infestans in the wild potato relative Solanum americanum was explored. S. americanum is the source of two late blight resistance genes, Rpi-amr1 and Rpi-amr3, that confer strong resistance against multiple P. infestans isolates. Here, Rpi-amr5, a paralogue of Rpi-amr1, was also found to confer resistance to P. infestans. Interestingly, in another accession, we identified an Rpi-amr5 allele (named Rpc2) which also confers strong resistance to Phytophthora capsici, which infects tomato and pepper. Two P. infestans effectors and three P. capsici effectors are recognised by both NLRs. It is currently unclear why Rpi-amr5 does not confer resistance to P. capsici. In Chapter 5, we characterized several other resistance genes to P. capsici. While they remain uncloned, there is potential for identifying additional Rpc genes and making Rpc-gene stacks to reduce the economic impact of P. capsici.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Chris White
Date Deposited:	18 Mar 2025 08:50
Last Modified:	18 Mar 2025 08:50
URI:	https://ueaeprints.uea.ac.uk/id/eprint/98768
DOI:

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