A complex NLR signalling network mediates immunity to diverse plant pathogens

Wu, Chih-Hang (2016) A complex NLR signalling network mediates immunity to diverse plant pathogens. Doctoral thesis, University of East Anglia.

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Both plants and animals rely on nucleotide-­binding domain leucine-­rich
repeat-­containing (NLR) proteins to respond to invading pathogens and
activate immune responses. An emerging concept in NLR biology is that
“sensor” NLR proteins are often paired with “helper” NLR proteins to mediate
immune signalling. However, the degree to which NLRs form signalling
networks beyond sensor and helper pairs is poorly understood. In this thesis,
I discovered that a large NLR immune signalling network with a complex
architecture mediates immunity to oomycetes, bacteria, viruses, nematodes,
and insects. Helper NLRs in the NRC (NLR-­required for cell death) family are
functionally redundant but display distinct specificities towards diverse sensor
NLRs. Several sensor NLRs, including Rx, Bs2 and Sw5b, signal via
interchangeable NRC2, NRC3 or NRC4, whereas some other sensor NLRs
have a more limited downstream spectrum. For example, Prf signals via
interchangeable NRC2 or NRC3 but not NRC4, and Rpi-­blb2 signals via only
NRC4. These helper/sensor NLRs form a unique phylogenetic superclade,
with the NRC clade sister to the sensor NLR clades. The network has
emerged over 100 million years ago from an NLR pair that diversified into up
to one half of the NLRs of asterids. I propose that this NLR network increases
evolvability and robustness of immune signalling to counteract rapidly evolving
plant pathogens.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Jackie Webb
Date Deposited: 31 Jan 2017 15:52
Last Modified: 31 Jan 2020 01:38
URI: https://ueaeprints.uea.ac.uk/id/eprint/62253


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