Characterizing the roles of Arabidopsis calmodulin-like protein, CML39, in hormonal regulation of early seedling development and fruit formation.
Calcium (Ca2+) is considered among the most ubiquitous and versatile second messengers in eukaryotes. Cytosolic Ca2+-oscillations are evoked by environmental stimuli such as biotic or abiotic stresses and developmental cues. In turn, these Ca2+signals are detected by Ca2+-binding proteins, termed Ca2+ sensors, that help coordinate physiological responses by binding to and regulating the activities of various proteins. Calmodulin (CaM) is an evolutionarily-conserved eukaryotic Ca2+ sensor involved in many signal transduction pathways. Interestingly, plants possess large families of unique Ca2+sensors related to CaM and known as calmodulin-like (CML) proteins. Several CMLs have been implicated in developmental and stress-response signalling but the roles of most CMLs remain unknown. We recently reported the importance of Arabidopsis CML39 in early seedling establishment (Bender et al 2013, Plant J: 76:634). CML39 knock-out (KO) mutants display developmental arrest in the absence of exogenous sucrose. Our ongoing phenotypic analysis of cml39 knock-out plants has identified several additional developmental abnormalities in these mutants. In comparison to wild-type plants, cml39 mutants display perturbations in response to exogenous hormones, altered fruit morphologies, and unusual germination properties. Qualitative and quantitative studies describing the phenotypic characteristics of cml39vs wild-type plants are presented. In addition, a putative interacting partner (CML39IP) of CML39 was identified through yeast-two-hybrid screens. Here, we present preliminary data for the delineation of the interaction domain along with the phenotypic analysis of KO mutants of CML39IP.