Protein Targeting and Vesicular Trafficking
Metcalf, Kasee , Falbel, Tanya , Muday, Gloria K .
Altered auxin transport and root development in the scd1 mutant.
Auxin transport polarity requires localization of IAA efflux protein complexes to the plasma membrane at one end of IAA transporting cells. This polarity is believed to be established and maintained by vesicular delivery and endosomal cycling of proteins in this complex. RAB GTPases and their interacting proteins mediate docking of vesicles at specific cellular locations and thereby facilitate targeted protein delivery. We have asked if IAA transport, IAA efflux proteins, and dependent physiological processes are altered in scd1 mutants, which have defects in a gene encoding a protein with similarity to RAB binding proteins. These mutants were originally isolated for their defect in stomatal cytokinesis, but also have profound cell expansion defects in roots and other cell types, which is a phenotype frequently linked to auxin response or transport. Two alleles were examined with a focus on scd1-1, which is a temperature sensitive mutant allele. The roots of scd1-1 are shorter than wild type and have few if any lateral roots when grown at the nonpermissive temperature. Gravitropism is also impaired in scd1-1 at the nonpermissive temperature. The root phenotypes are also reversible when plants are returned to the permissive temperature. Acropetal (shoot to root) IAA transport, a primary source of auxin for root development, is also reduced within several hours after transfer to this nonpermissive temperature. We have examined the localization of PIN1::GFP and found that when scd1-1 is grown at the nonpermissive temperature, PIN1::GFP localization is less constrained to the basal plasma membrane and is also found in organelles within the cytoplasm. Together these experiments suggest that SCD1 may play an important role in targeting IAA transport proteins to the plasma membrane and in specifying auxin transport polarity.
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1 - Wake Forest University, Biology
2 - University of Wisconsin-Eu Clare, Biology Department
3 - Wake Forest University, Biology, 1834 Wake Forest Road, Room 226 Winston Hall, Winston Salem, NC, 27106, USA
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM