An investigation into the role of cytosolic free Ca2+ in Salicylic acid mediation of disease resistance in Arabidopsis

Salicylic acid (SA) accumulation upon pathogen attack is a fundamental requirement for the activation of numerous plant defence mechansms. Cytosolic free Ca2+ ([Ca2+]c) is a ubiquitous signalling molecule involved in a host of cellular processes. Using transgenic Arabidopsis thaliana seedlings expressing the Ca2+-sensitive photoprotein aequorin, we previously reported a rapid and transient increase in [Ca2+]c upon application of exogenous SA. We now investigated the characteristics of the SA-induced [Ca2+]c increase and report that the majority of the response is derived from internal stores. It appears likely that SA triggers Ca2+-induced Ca2+-release. Preliminary evidence suggests a role for the SA-induced [Ca2+]c increase in the regulation of NPR1 expression since modulation of the SA-induced [Ca2+]c response with the extracellular Ca2+ chelator BAPTA causes a reduction in NPR1 mRNA levels. We have isolated two putative mutants that are defective in their ability to produce a SA-induced [Ca2+]c increase. Characterisation of these mutants is underway and will prove invaluable in identifying the components or events that cause the SA-induced [Ca2+]c transient, thereby aiding in the understanding of the role of [Ca2+]c in SA-mediated signal transduction.

Grantor

Department of Molecular and Cell Biology

Year dc:date.issued

2001

Author dc:creator

• Petersen, Lindsay Natalie

Advisor dc:contributor.advisor

• Denby, Katherine J

• Molecular and Cell Biology

Handle dc:identifier.uri

http://hdl.handle.net/11427/40285

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/40285