Poster: Cell Walls

Abs # 1256: Characterization of the cellular mechanisms controlling the differential localization and function of ATPRP1 and ATPRP3, two root hair specific proline-rich cell wall proteins in arabidopsis

Presenter:	Tierney, Mary , Mary.Tierney@uvm.edu
Authors	Tierney, Mary  (A)   Zhang, Xu  (A)
Affiliations:	(A): University of Vermont

Structural cell wall proteins play an important role in modifying the extracellular matrix of specific cell types as they expand and mature. AtPRP1 and AtPRP3 encode two proline-rich proteins in arabidopsis that are expressed exclusively in root hairs. We have recently shown that ATPRP1 accumulates within the cell wall of the trichoblast at the base of the root hair while ATPRP3 is first detected within the cell wall of the emerging root hair tip and subsequently becomes insolubilized within the root hair cell wall. These data indicate that ATPRP1 and ATPRP3 are not redundant in their function and are likely to play unique roles in modeling the structure of the root hair cell wall. Using transgenic plants expressing epitope-tagged versions of ATPRP1 and ATPRP3, we are examining whether this differential localization is due to transcriptional control (promoter-swaps) or differential protein sorting via their signal sequence (signal sequence swaps). In addition, we have identified T-DNA insertion null alleles for both ATPRP1 and ATPRP3. Previous studies have shown that atprp3-1 mutants exhibit both root hair and whole plant phenotypes that can be complemented by a wild type copy of this gene. We are currently characterizing two null alleles for ATPRP1 to determine whether similar phenotypes are associated with the absence of this protein within the trichoblast cell wall surrounding the base of the root hair. In addition, we have generated an atprp3/atprp1 double mutant to determine if the phenotypes associated with the absence of ATPTP3 in the cell wall are enhance or modified in the double mutant background.