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Nat Commun. 2018 Apr 30;9(1):1718. doi: 10.1038/s41467-018-04140-9.

An effector from the Huanglongbing-associated pathogen targets citrus proteases.

Author information

1
Department of Microbiology and Plant Pathology, University of California, Riverside, 92521, CA, USA.
2
Department of Plant Pathology, University of California, Davis, 95616, CA, USA.
3
Center for Plant Cell Biology, University of California, Riverside, 92521, CA, USA.
4
Citrus Research and Education Center, University of Florida, Lake Alfred, 33850, FL, USA.
5
Citrus Center, Texas A&M University, Weslaco, 78599, TX, USA.
6
Department of Chemistry, University of California, Riverside, 92521, CA, USA.
7
College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China.
8
University of Oxford, Oxford, OX1 2JD, UK.
9
Department of Plant Pathology, University of California, Davis, 95616, CA, USA. glcoaker@ucdavis.edu.
10
Department of Microbiology and Plant Pathology, University of California, Riverside, 92521, CA, USA. wenbo.ma@ucr.edu.
11
Center for Plant Cell Biology, University of California, Riverside, 92521, CA, USA. wenbo.ma@ucr.edu.

Abstract

The citrus industry is facing an unprecedented challenge from Huanglongbing (HLB). All cultivars can be affected by the HLB-associated bacterium 'Candidatus Liberibacter asiaticus' (CLas) and there is no known resistance. Insight into HLB pathogenesis is urgently needed in order to develop effective management strategies. Here, we use Sec-delivered effector 1 (SDE1), which is conserved in all CLas isolates, as a molecular probe to understand CLas virulence. We show that SDE1 directly interacts with citrus papain-like cysteine proteases (PLCPs) and inhibits protease activity. PLCPs are defense-inducible and exhibit increased protein accumulation in CLas-infected trees, suggesting a role in citrus defense responses. We analyzed PLCP activity in field samples, revealing specific members that increase in abundance but remain unchanged in activity during infection. SDE1-expressing transgenic citrus also exhibit reduced PLCP activity. These data demonstrate that SDE1 inhibits citrus PLCPs, which are immune-related proteases that enhance defense responses in plants.

PMID:
29712915
PMCID:
PMC5928222
DOI:
10.1038/s41467-018-04140-9
[Indexed for MEDLINE]
Free PMC Article

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