Browse Articles

Article|29 Nov 2017|OPEN
Reprogramming of a defense signaling pathway in rough lemon and sweet orange is a critical element of the early response to ‘Candidatus Liberibacter asiaticus’
Chunxian Chen2 , Jiqiang Yao3 , Qibin Yu1,4 , Dongliang Du1 , Ming Huang1 , Fahong Yu3 and Ronald H Brlansky1 , Frederick G. Gmitter Jr,1 ,
1University of Florida, Institute of Food and Agricultural Sciences, Citrus Research and Education Center, Lake Alfred, FL 33850, USA.
2USDA, ARS, SEFTNRL, 21 Dunbar Road, Byron, GA 31008, USA
3Interdisciplinary Center for Biotechnology Research, University of Florida, 2033 Mowry Road, Gainesville, Florida 32611, USA
4Submitting author
*Corresponding author. E-mail: fgmitter@ufl.edu

Horticulture Research 4,
Article number: 63 (2017)
doi: https://doi.org/10.1038/hortres.2017.63
Views: 970

Received: 26 May 2017
Revised: 11 Oct 2017
Accepted: 11 Oct 2017
Published online: 29 Nov 2017

Abstract

Huanglongbing (HLB) in citrus infected by Candidatus Liberibacter asiaticus (CLas) has caused tremendous losses to the citrus industry. No resistant genotypes have been identified in citrus species or close relatives. Among citrus varieties, rough lemon (Citrus jambhiri) has been considered tolerant due to its ability to produce a healthy flush of new growth after infection. The difference between tolerance and susceptibility is often defined by the speed and intensity of a plant’s response to a pathogen, especially early defense responses. RNA-seq data were collected from three biological replicates of CLas- and mock-inoculated rough lemon and sweet orange at week 0 and 7 following infection. Functional analysis of the differentially expressed genes (DEGs) indicated that genes involved in the mitogen activated protein kinase (MAPK) signaling pathway were highly upregulated in rough lemon. MAPK induces the transcription of WRKY and other transcription factors which potentially turn on multiple defense-related genes. A Subnetwork Enrichment Analysis further revealed different patterns of regulation of several functional categories, suggesting DEGs with different functions were subjected to reprogramming. In general, the amplitude of the expression of defense-related genes is much greater in rough lemon than in sweet orange. A quantitative disease resistance response may contribute to the durable tolerance level to HLB observed in rough lemon.