The Arabidopsis Calcineurin B-Like10 Calcium Sensor Couples Environmental Signals to Developmental Responses

Persistent Link:
http://hdl.handle.net/10150/202993
Title:
The Arabidopsis Calcineurin B-Like10 Calcium Sensor Couples Environmental Signals to Developmental Responses
Author:
Monihan, Shea
Issue Date:
2011
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Calcium is a component of signal transduction pathways that allow plants to respond to numerous endogenous and environmental signals during growth and development. Calcium-mediated signaling involves multiple components including: 1) channels, pumps, and exchangers that act in concert to generate a change in cytosolic calcium, 2) calcium-binding proteins that sense the calcium change, and 3) downstream target proteins that modify enzyme activity and gene expression needed for the subsequent response. One method for achieving specificity during calcium signaling is through regulation of the calcium-binding proteins that perceive changes in cytosolic calcium. These proteins can be regulated through differences in expression in response to stimuli, localization within the cell or plant, affinity for calcium, and interaction with downstream target proteins; all of which can result in specific cellular responses. My projects have focused on the Arabidopsis thaliana (Arabidopsis) CALCINEURIN B-LIKE10 (CBL10) calcium-binding protein, and specifically on understanding: 1) how post-transcriptional regulation of the CBL10 gene is used to modulate seedling growth in saline conditions (salinity), and 2) CBL10’s function in the flower during growth in salinity. In addition, 3) I have examined the roles of two putative CBL10-interacting proteins in plant growth and development. CBL10 is alternatively spliced into two transcripts; CBL10 encoding the characterized, full-length protein and CBL10 LONG A (CBL10LA) encoding a putative truncated protein due to a pre-mature termination codon within a retained intron. When seedlings are grown in the absence of salinity, both alternatively spliced transcripts are detected; however, in response to salinity, levels of the CBL10LA transcript are reduced. My data suggest a model in which the relative abundance of the two transcripts regulates the SALT-OVERLY-SENSITIVE (SOS) pathway involved in maintaining cellular sodium ion homeostasis. The presence of CBL10LA in the absence of salinity ensures that the SOS pathway is inactive. The removal of CBL10LA in response to saline conditions results in CBL10 activation of the SOS pathway to prevent sodium ions from accumulating to toxic levels in the cytosol. Successful fertilization during flowering requires the coordinated development of stamens and pistils. Stamens must elongate and anthers dehisce to release pollen onto the stigma while the pistil prepares to receive the pollen and promote growth and targeting of the female gametophyte. When the cbl10 mutant is grown in salinity, flowers are sterile due to decreased stamen elongation, reduced anther dehiscence, and abnormal pistil development. My studies demonstrated that the SOS pathway is not involved in maintaining flower development in salinity and indicate that CBL10 functions in different pathways to regulate vegetative and reproductive development during growth in saline conditions. An in silico search for Arabidopsis proteins that might interact with CBL10 resulted in the identification of two components of the Mediator complex involved in the regulation of transcription in eukaryotes. While additional studies I carried out suggest that interaction with CBL10 is unlikely, I have shown that these proteins are important for plant growth in high levels of chloride and in maintenance of growth in short-day conditions.
Type:
text; Electronic Dissertation
Keywords:
calcium sensor; CBL10; development; signal transduction; Plant Science; alternative splicing; Arabidopsis
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Plant Science
Degree Grantor:
University of Arizona
Advisor:
Schumaker, Karen

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleThe Arabidopsis Calcineurin B-Like10 Calcium Sensor Couples Environmental Signals to Developmental Responsesen_US
dc.creatorMonihan, Sheaen_US
dc.contributor.authorMonihan, Sheaen_US
dc.date.issued2011-
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractCalcium is a component of signal transduction pathways that allow plants to respond to numerous endogenous and environmental signals during growth and development. Calcium-mediated signaling involves multiple components including: 1) channels, pumps, and exchangers that act in concert to generate a change in cytosolic calcium, 2) calcium-binding proteins that sense the calcium change, and 3) downstream target proteins that modify enzyme activity and gene expression needed for the subsequent response. One method for achieving specificity during calcium signaling is through regulation of the calcium-binding proteins that perceive changes in cytosolic calcium. These proteins can be regulated through differences in expression in response to stimuli, localization within the cell or plant, affinity for calcium, and interaction with downstream target proteins; all of which can result in specific cellular responses. My projects have focused on the Arabidopsis thaliana (Arabidopsis) CALCINEURIN B-LIKE10 (CBL10) calcium-binding protein, and specifically on understanding: 1) how post-transcriptional regulation of the CBL10 gene is used to modulate seedling growth in saline conditions (salinity), and 2) CBL10’s function in the flower during growth in salinity. In addition, 3) I have examined the roles of two putative CBL10-interacting proteins in plant growth and development. CBL10 is alternatively spliced into two transcripts; CBL10 encoding the characterized, full-length protein and CBL10 LONG A (CBL10LA) encoding a putative truncated protein due to a pre-mature termination codon within a retained intron. When seedlings are grown in the absence of salinity, both alternatively spliced transcripts are detected; however, in response to salinity, levels of the CBL10LA transcript are reduced. My data suggest a model in which the relative abundance of the two transcripts regulates the SALT-OVERLY-SENSITIVE (SOS) pathway involved in maintaining cellular sodium ion homeostasis. The presence of CBL10LA in the absence of salinity ensures that the SOS pathway is inactive. The removal of CBL10LA in response to saline conditions results in CBL10 activation of the SOS pathway to prevent sodium ions from accumulating to toxic levels in the cytosol. Successful fertilization during flowering requires the coordinated development of stamens and pistils. Stamens must elongate and anthers dehisce to release pollen onto the stigma while the pistil prepares to receive the pollen and promote growth and targeting of the female gametophyte. When the cbl10 mutant is grown in salinity, flowers are sterile due to decreased stamen elongation, reduced anther dehiscence, and abnormal pistil development. My studies demonstrated that the SOS pathway is not involved in maintaining flower development in salinity and indicate that CBL10 functions in different pathways to regulate vegetative and reproductive development during growth in saline conditions. An in silico search for Arabidopsis proteins that might interact with CBL10 resulted in the identification of two components of the Mediator complex involved in the regulation of transcription in eukaryotes. While additional studies I carried out suggest that interaction with CBL10 is unlikely, I have shown that these proteins are important for plant growth in high levels of chloride and in maintenance of growth in short-day conditions.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectcalcium sensoren_US
dc.subjectCBL10en_US
dc.subjectdevelopmenten_US
dc.subjectsignal transductionen_US
dc.subjectPlant Scienceen_US
dc.subjectalternative splicingen_US
dc.subjectArabidopsisen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplinePlant Scienceen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorSchumaker, Karenen_US
dc.contributor.committeememberYadegari, Raminen_US
dc.contributor.committeememberLarkins, Brianen_US
dc.contributor.committeememberTax, Fransen_US
dc.contributor.committeememberPalanivelu, Ravishankaren_US
dc.contributor.committeememberSchumaker, Karenen_US
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