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.

Details

Title
An effector from the Huanglongbing-associated pathogen targets citrus proteases
Author
Clark, Kelley 1 ; Franco, Jessica Yvette 2 ; Schwizer, Simon 3 ; Pang, Zhiqian 4 ; Hawara, Eva 1 ; Liebrand, Thomas W H 2   VIAFID ORCID Logo  ; Pagliaccia, Deborah 1 ; Zeng, Liping 3 ; Gurung, Fatta B 5 ; Wang, Pengcheng 6 ; Shi, Jinxia 7 ; Wang, Yinsheng 6 ; Ancona, Veronica 5 ; Renier A L van der Hoorn 8 ; Wang, Nian 4   VIAFID ORCID Logo  ; Coaker, Gitta 2   VIAFID ORCID Logo  ; Ma, Wenbo 3   VIAFID ORCID Logo 

1  Department of Microbiology and Plant Pathology, University of California, Riverside, CA, USA 
2  Department of Plant Pathology, University of California, Davis, CA, USA 
3  Department of Microbiology and Plant Pathology, University of California, Riverside, CA, USA; Center for Plant Cell Biology, University of California, Riverside, CA, USA 
4  Citrus Research and Education Center, University of Florida, Lake Alfred, FL, USA 
5  Citrus Center, Texas A&M University, Weslaco, TX, USA 
6  Department of Chemistry, University of California, Riverside, CA, USA 
7  Department of Microbiology and Plant Pathology, University of California, Riverside, CA, USA; College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, China 
8  University of Oxford, Oxford, UK 
Pages
1-11
Publication year
2018
Publication date
Apr 2018
Publisher
Nature Publishing Group
e-ISSN
20411723
Source type
Scholarly Journal
Language of publication
English
DOI
https://doi.org/10.1038/s41467-018-04140-9
ProQuest document ID
2032751080
Copyright
© 2018. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.