{"id":{"repo_id":"cape-town","oai_identifier":"oai:open.uct.ac.za:11427/40285"},"canonical_url":"https://search.dev.ndltd.org/etd/cape-town/oai:open.uct.ac.za:11427/40285","repository":{"repo_id":"cape-town","name":"University of Cape Town","base_url":"https://open.uct.ac.za/oai/request"},"display":{"title":"An investigation into the role of cytosolic free Ca2+ in Salicylic acid mediation of disease resistance in Arabidopsis","abstract":"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.","abstract_html":"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.","abstract_has_math":false,"creators":["Petersen, Lindsay Natalie"],"institution":"Department of Molecular and Cell Biology","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Denby, Katherine J"],"committee_chairs":[],"committee_members":[],"year":2001,"date_issued":"2001","date_published":"2001","updated_at":"2026-07-22T22:23:17Z","subjects":["Molecular and Cell Biology"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/11427/40285","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Denby, Katherine J"]},{"key":"dc:creator","label":"Author","values":["Petersen, Lindsay Natalie"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2024-07-04T13:43:30Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2024-07-04T13:43:30Z"]},{"key":"dc:date.issued","label":"Date","values":["2001"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Department of Molecular and Cell Biology"]},{"key":"dc:type","label":"Dc Type","values":["Thesis / Dissertation"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Masters","MSc"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Molecular and Cell Biology"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/11427/40285"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["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."]},{"key":"dc:title","label":"Title","values":["An investigation into the role of cytosolic free Ca2+ in Salicylic acid mediation of disease resistance in Arabidopsis"]}]}],"canonical_facts":{"dc:contributor.advisor":["Denby, Katherine J"],"dc:creator":["Petersen, Lindsay Natalie"],"dc:date.accessioned":["2024-07-04T13:43:30Z"],"dc:date.available":["2024-07-04T13:43:30Z"],"dc:date.issued":["2001"],"dc:description.abstract":["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."],"dc:identifier.uri":["http://hdl.handle.net/11427/40285"],"dc:publisher.department":["Department of Molecular and Cell Biology"],"dc:subject":["Molecular and Cell Biology"],"dc:title":["An investigation into the role of cytosolic free Ca2+ in Salicylic acid mediation of disease resistance in Arabidopsis"],"dc:type":["Thesis / Dissertation"],"dc:type.qualificationlevel":["Masters","MSc"]},"updated_at":"2026-07-22T22:23:17Z"}