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dc.contributor.authorMatthus, Elsa
dc.date.accessioned2019-03-06T10:57:47Z
dc.date.available2019-03-06T10:57:47Z
dc.date.issued2019-02-20
dc.date.submitted2018-09-28
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/290260
dc.description.abstractLow bioavailability of phosphate (P) due to low concentration and high immobility in soils is a key limiting factor in crop production. Application of excess amounts of P fertilizer is costly and by no means sustainable, as world-wide P resources are finite and running out. To facilitate the breeding of crops adapted to low-input soils, it is essential to understand the consequences of P deficiency. The second messenger calcium (Ca2+) is known to signal in plant development and stress perception, and most recently its direct role in signalling nutrient availability and deficiency has been partially elucidated. The use of Ca2+ as a signal has to be tightly controlled, as Ca2+ easily complexes with P groups and therefore is highly toxic to cellular P metabolism. It is unknown whether Ca2+ signals P availability or whether signalling is altered under P starvation conditions. The aim of this PhD project was to characterise the use of Ca2+ ions, particularly cytosolic free Ca2+ ([Ca2+]cyt), in stress signalling by P-starved roots of the model plant Arabidopsis thaliana. The hypothesis was that under P starvation and a resulting decreased cellular P pool, the use of [Ca2+]cyt may have to be restricted to avoid cytotoxic complexation of Ca2+ with limited P groups. Employing a range of genetically encoded Ca2+ reporters in Arabidopsis, P starvation but not nitrogen starvation was found to strongly dampen the root [Ca2+]cyt increases evoked by mechanical, salt, osmotic, and oxidative stress as well as by extracellular nucleotides. The strongly altered root [Ca2+]cyt response to extracellular nucleotides was shown to manifest itself during seedling development under chronic P deprivation, but could be reversed by P resupply. Fluorescent imaging elucidated that P-starved roots showed a normal [Ca2+]cyt response to extracellular nucleotides at the apex, but a strongly dampened [Ca2+]cyt response in distal parts of the root tip, correlating with high reactive oxygen species (ROS) levels induced by P starvation. Excluding iron, as well as P, rescued the altered [Ca2+]cyt response, and restored ROS levels to those seen under nutrient-replete conditions. P availability was not signalled through [Ca2+]cyt. In another part of this PhD project, a library of 77 putative Ca2+ channel mutants was compiled and screened for aberrant root hair growth under P starvation conditions. No mutant line showed aberrant root hair growth. These results indicate that P starvation strongly affects stress-induced [Ca2+]cyt modulations. The data generated in this thesis further understanding of how plants can integrate nutritional and environmental cues, adding another layer of complexity to the use of Ca2+ as a signal transducer.
dc.description.sponsorshipBBSRC DTP
dc.language.isoen
dc.rightsAll rights reserved
dc.rightsAll Rights Reserveden
dc.rights.urihttps://www.rioxx.net/licenses/all-rights-reserved/en
dc.subjectplant
dc.subjectroot
dc.subjectArabidopsis thaliana
dc.subjectArabidopsis
dc.subjectcalcium signalling
dc.subjectplant nutrition
dc.subjectphosphate nutrition
dc.subjectiron nutrition
dc.subjectreactive oxygen species
dc.subjectabiotic stress
dc.subjectextracellular nucleotide signalling
dc.subjectATP
dc.subjectfluorescence microscopy
dc.subjectratiometric imaging
dc.subjectGCaMP3
dc.subjectaequorin
dc.titlePhosphate starvation alters calcium signalling in roots of Arabidopsis thaliana
dc.typeThesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnameDoctor of Philosophy (PhD)
dc.publisher.institutionUniversity of Cambridge
dc.publisher.departmentPlant Sciences
dc.date.updated2019-03-06T09:39:02Z
dc.identifier.doi10.17863/CAM.37488
dc.contributor.orcidMatthus, Elsa [0000-0002-7845-3945]
dc.publisher.collegeChurchill College
dc.type.qualificationtitlePhD in Plant Sciences
cam.supervisorDavies, Julia M
cam.thesis.fundingtrue


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