Cell/Development/Systems

Abstract

CS-10-3 - ACAP-type ARF-GAPs as signaling hubs for the maintenance of root hair cell polarity

Sunday, July 15
3:58 PM - 4:18 PM

Root hairs are single cell cylindrical projections that emerge from root epidermal cells. By expanding the effective radius of the root, root hairs play crucial roles in water and nutrient acquisition especially under conditions in which such resources are limiting. The cylindrical shape of a root hair cell is the result of tip growth, the targeted delivery and secretion of vesicles to the apical-most dome of the cell. We showed previously that an ACAP-type ARF-GAP called AGD1 (for ARF-GAP Domain 1) is required for maintaining root hair polarity in Arabidopsis thaliana. Loss-of-function AGD1 leads to root hairs with undulating growth and two growing points due to disrupted cytoskeletal dynamics and tip-focused secretion. We studied AGD1 in more detail by following the localization of a functional AGD1-GFP during root hair development. Full length AGD1-GFP localized to unknown cytoplasmic bodies and was recruited to specific regions of the root hair plasma membrane (PM). AGD1-GFP marked the the site of root hair bulge formation and remained at the PM at the root hair apical dome, but only during periods of slower growth. During rapid tip growth, AGD1-GFP was confined to the PM of the root hair flanks. AGD1 contains four domains: Bin1-amphiphysin-Rvs167p/Rvs161p (BAR), PH (Pleckstrin Homology), GAP (GTPase Activating Protein) and two ankyrin repeats. Deletion analysis revealed that the PH domain is the minimal unit required for recruitment of AGD1 to the PM by binding to pools of  phosphatidylinositol-4-phosphate (PI4P) at the root hair tip. Our results indicate that PM-localized AGD1 functions not only as a GAP but also as a signaling platform that coordinates membrane trafficking and cytoskeletal dynamics during root hair development (supported by the Noble Research Institute and National Aeronautics and Space Administration (grant NNX12AM94G to EBB).


 

Co-Authors

Cheolmin Yoo – Gulf Coast Research and Education Center, University of Florida; Satoshi Naramoto – Department of Biomolecular Sciences, Tohoku University, Japan; J. Alan Sparks – Noble Research Institute LLC

Elison B. Blancaflor

Professor
Noble Research Institute LLC

Presentation(s):

Send Email for Elison Blancaflor


Assets

CS-10-3 - ACAP-type ARF-GAPs as signaling hubs for the maintenance of root hair cell polarity



Attendees who have favorited this

Please enter your access key

The asset you are trying to access is locked. Please enter your access key to unlock.

Send Email for ACAP-type ARF-GAPs as signaling hubs for the maintenance of root hair cell polarity