Year of Publication

2010

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Agriculture

Department

Plant Pathology

First Advisor

Dr. Pradeep Kachroo

Abstract

Systemic acquired resistance (SAR) is initiated upon recognition of specific microbial effectors by cognate plant resistance proteins and immunizes distal tissues of plants against secondary infections. SAR involves the generation of a mobile signal at the site of primary infection, which then translocates to and activates defense responses in the distal tissues via some unknown mechanism(s). This study shows that an ACYL CARRIER PROTEIN 4 (ACP4), GLABRA1 (GL1) and ACYL CARRIER BINDING PROTEINS (ACBP) are required for the processing of the mobile SAR signal in distal tissues of Arabidopsis. Although acp4, gl1 and acbp plants generate the mobile signal, they are unable to respond to this signal to induce systemic immunity. A defective SAR in acp4, gl1 and acbp plants is not associated with salicylic acid (SA)-, methyl SA-, or jasmonic acid-mediated pathways but is related to the presence of an abnormal cuticle on acp4, gl1 and acbp plants. Other genetic mutations impairing the cuticle also compromised SAR. An intact cuticle was only necessary during the time when the mobile signal is generated and translocated to the distal tissues. A novel role for the plant cuticle as the site for SAR-related molecular signaling is demonstrated.

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