The Arabidopsis CALCINEURIN B-LIKE10 calcium sensor couples environmental signals to developmental responses.

摘要

To understand how specificity is achieved during calcium-mediated signaling in plants, my projects have focused on understanding how post-transcriptional regulation of Arabidopsis thaliana (Arabidopsis) CALCINEURIN B-LIKE10 (CBL10) calcium sensor gene modulates seedling growth in saline conditions (salinity) and CBL10 's function in the flower during growth in salinity. In addition, 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 without 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 elongate and anthers dehisce to release pollen onto the stigma while the pistil receives the pollen and promotes pollen tube growth and targeting to the female gametophyte. When the cbl10 mutant is grown in salinity, flowers are sterile due to reduced stamen elongation and anther dehiscence, and abnormal pistil development. My studies demonstrated that the SOS pathway is not involved in maintaining flower development in salinity and that CBL10 functions in different pathways to regulate vegetative and reproductive development.;An in silico search for Arabidopsis proteins that interact with CBL10 resulted in the identification of two components of the Mediator complex involved in the regulation of transcription in eukaryotes. While my studies indicate 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.