Open AccessResistance to citrus canker induced by a variant of Xanthomonas citri ssp. citri is associated with a hypersensitive cell death response involving autophagy‐associated vacuolar processes
Author(s) -
Roeschlin Roxana A.,
Favaro María A.,
Chiesa María A.,
Alemano Sergio,
Vojnov Adrián A.,
Castagnaro Atilio P.,
Filippone María P.,
Gmitter Frederick G.,
Gadea José,
Marano María R.
Publication year - 2017
Publication title -
molecular plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.945
H-Index - 103
eISSN - 1364-3703
pISSN - 1464-6722
DOI - 10.1111/mpp.12489
Subject(s) - xanthomonas citri , citrus canker , biology , hypersensitive response , autophagy , canker , pathogen , microbiology and biotechnology , xanthomonas , programmed cell death , xanthomonas oryzae , plant disease resistance , botany , gene , bacteria , genetics , apoptosis
Summary Xanthomonas citri ssp. citri ( X. citri ) is the causal agent of Asiatic citrus canker, a disease that seriously affects most commercially important Citrus species worldwide. We have identified previously a natural variant, X. citri A T , that triggers a host‐specific defence response in Citrus limon . However, the mechanisms involved in this canker disease resistance are unknown. In this work, the defence response induced by X. citri A T was assessed by transcriptomic, physiological and ultrastructural analyses, and the effects on bacterial biofilm formation were monitored in parallel. We show that X. citri A T triggers a hypersensitive response associated with the interference of biofilm development and arrest of bacterial growth in C. limon . This plant response involves an extensive transcriptional reprogramming, setting in motion cell wall reinforcement, the oxidative burst and the accumulation of salicylic acid (SA) and phenolic compounds. Ultrastructural analyses revealed subcellular changes involving the activation of autophagy‐associated vacuolar processes. Our findings show the activation of SA‐dependent defence in response to X. citri A T and suggest a coordinated regulation between the SA and flavonoid pathways, which is associated with autophagy mechanisms that control pathogen invasion in C. limon . Furthermore, this defence response protects C. limon plants from disease on subsequent challenges by pathogenic X. citri . This knowledge will allow the rational exploitation of the plant immune system as a biotechnological approach for the management of the disease.