Submitted to: Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2002
Publication Date: N/A
Citation: Interpretive Summary: The uptake, transport, and distribution of calcium in developing plant tissues is one of many important processes that determine the quality, efficiency, and stress tolerance of crop plants. Other scientists, using Arabidopsis as a model plant system, have identified genes which may be involved in calcium transport mechanisms. One of these genes corresponds to a presumably membrane-bound protein whose function in plant tissue is not yet known. In this study, immunological techniques were used to determine the localization of this protein in developing Arabidopsis plants, and the gene's messenger-RNA level, which indicates when and where the gene is being expressed, was quantified. Also, experiments were performed to confirm that the gene code corresponds to a protein which is membrane-bound in plant tissue. The results suggest that this protein may be involved in regulating calcium transport or similar processes in plants. This information will be used by scientists and plant breeders to develop strategies for plant improvement.
Technical Abstract: The accumulation and localization of the transcript and protein corresponding to the gene that encodes the putative glutamate receptor isoenzyme 3.2 in Arabidopsis thaliana (AtGLR3.2) is reported. Polyclonal antibodies, raised to the C-terminal region of AtGLR3.2, were used to determine that the putative plant glutamate receptor is an integral membrane protein with an apparent molecular weight of 110 kD. Northern blot analysis revealed temporal accumulation of the AtGLR3.2 transcript in developing seedlings. Accumulation of the AtGLR3.2 transcript was highest in rapidly dividing tissues. Protein immunoblot analysis established that the presence of the AtGLR3.2 protein mirrored, in most cases, the accumulation of the AtGLR3.2 transcript. Affinity purified antibodies were used to localize the AtGLR3.2 protein in thin tissue sections. Immunohistochemical staining was intense and generalized in the rapidly dividing tissues of the developing floral buds, but mostly confined to the vascular tissue of the more mature hypocotyl, leaf and floral shoot tissues. Localization of the AtGLR3.2 protein to the rapidly growing tissues and vascular tissues is consistent with its proposed role in the translocation of calcium.