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Proc Natl Acad Sci U S A. 2017 Jul 25;114(30):8113-8118. doi: 10.1073/pnas.1702041114. Epub 2017 Jul 11.

NLR network mediates immunity to diverse plant pathogens.

Author information

1
The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, United Kingdom.
2
Plant Breeding, Wageningen University and Research, Wageningen 6708 PB, The Netherlands.
3
Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom.
4
Division of Genomics and Breeding, Iwate Biotechnology Research Center, Iwate 024-0003, Japan.
5
Laboratory of Crop Evolution, Graduate School of Agriculture, Kyoto University, Kyoto 606-8501, Japan.
6
The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, United Kingdom; sophien.kamoun@tsl.ac.uk.

Abstract

Both plants and animals rely on nucleotide-binding domain and leucine-rich repeat-containing (NLR) proteins to respond to invading pathogens and activate immune responses. An emerging concept of NLR function is that "sensor" NLR proteins are paired with "helper" NLRs to mediate immune signaling. However, our fundamental knowledge of sensor/helper NLRs in plants remains limited. In this study, we discovered a complex NLR immune network in which helper NLRs in the NRC (NLR required for cell death) family are functionally redundant but display distinct specificities toward different sensor NLRs that confer immunity to oomycetes, bacteria, viruses, nematodes, and insects. The helper NLR NRC4 is required for the function of several sensor NLRs, including Rpi-blb2, Mi-1.2, and R1, whereas NRC2 and NRC3 are required for the function of the sensor NLR Prf. Interestingly, NRC2, NRC3, and NRC4 redundantly contribute to the immunity mediated by other sensor NLRs, including Rx, Bs2, R8, and Sw5. NRC family and NRC-dependent NLRs are phylogenetically related and cluster into a well-supported superclade. Using extensive phylogenetic analysis, we discovered that the NRC superclade probably emerged over 100 Mya from an NLR pair that diversified to constitute up to one-half of the NLRs of asterids. These findings reveal a complex genetic network of NLRs and point to a link between evolutionary history and the mechanism of immune signaling. We propose that this NLR network increases the robustness of immune signaling to counteract rapidly evolving plant pathogens.

KEYWORDS:

evolution; host–microbe interactions; immunity

Comment in

PMID:
28698366
PMCID:
PMC5544293
DOI:
10.1073/pnas.1702041114
[Indexed for MEDLINE]
Free PMC Article

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