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ARS Home » Northeast Area » Kearneysville, West Virginia » Appalachian Fruit Research Laboratory » Innovative Fruit Production, Improvement, and Protection » Research » Publications at this Location » Publication #344161

Research Project: Improving Stress and Disease Resistance in Tree Fruit Crops

Location: Innovative Fruit Production, Improvement, and Protection

Title: Signalling requirements for Erwinia amylovora-induced disease resistance, callose deposition and cell growth in the non-host Arabidopsis thaliana

Author
item Hamdoun, Safae - University Of Maryland
item Gao, Min - University Of Maryland
item Gill, Manroop - University Of Maryland
item Kwon, Ashley - University Of Maryland
item Norelli, John (jay) - Jay
item Lu, Hua - University Of Maryland

Submitted to: Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/29/2017
Publication Date: 10/17/2017
Citation: Hamdoun, S., Gao, M., Gill, M., Kwon, A., Norelli, J.L., Lu, H. 2017. Signalling requirements for Erwinia amylovora-induced disease resistance, callose deposition and cell growth in the non-host Arabidopsis thaliana. Molecular Plant Pathology. 19(5):1090-1103. https://doi.org/10.1111/mpp.12588.
DOI: https://doi.org/10.1111/mpp.12588

Interpretive Summary: Fire blight, caused by the bacterium Erwinia amylovora, is a devastating bacterial disease of apple trees that results in severe economic losses. The nonhost plant Arabidopsis serves as a powerful system for the study of plant resistance to fire blight. When Arabidopsis was challenged with the fire blight bacteria, we found that Arabidopsis activated strong defense signaling mediated by the plant hormone salicylic acid (SA) with kinetics and amplitude similar to that caused by other known bacterial pathogens of Arabidopsis. Genetic analysis further revealed that SA signaling is required for fire blight resistance. The fire blight bacteria induced massive callose deposition in the infected leaves and we also observed tumor-like growths on E. amylovora-infected Arabidopsis leaves. Together our data reveals signaling requirements for E. amylovora-induced disease resistance, callose deposition, and cell fate change in the nonhost plant Arabidopsis. Knowledge from this study could facilitate better understanding of mechanisms of host defense against the fire blight bacteria and eventually improving host resistance to the pathogen.

Technical Abstract: Erwinia amylovora is the causal agent of the fire blight disease in some plants of the Rosaceae family. The nonhost plant Arabidopsis serves as a powerful system to dissect mechanisms of resistance to E. amylovora. Although not yet known to mount gene-for-gene resistance to E. amylovora, we found that Arabidopsis activated strong defense signaling mediated by salicylic acid (SA) with kinetics and amplitude similar to that induced by the resistance protein RPM1 recognition of bacterial effector avrRpm1. Genetic analysis further revealed that SA signaling but not those mediated by ethylene and jasmonic acid is required for E. amylovora resistance. E. amylovora induces massive callose deposition on the infected leaves, which is independent of SA, ET, and JA signaling and is necessary for E. amylovora resistance in Arabidopsis. We also observed tumor-like growths on E. amylovora-infected Arabidopsis leaves, which contain enlarged mesophyll cells with increased DNA content and are likely a result of endoreplication. The formation of such growths is largely independent of SA signaling and some E. amylovora effectors. Together our data reveal signaling requirements for E. amylovora-induced disease resistance, callose deposition, and cell fate change in the nonhost plant Arabidopsis. Knowledge from this study could facilitate better understanding of mechanisms of host defense against E. amylovora and eventually improving host resistance to the pathogen.