The Nonspecific Lipid Transfer Protein AtLtpI-4 Is Involved in Suberin Formation of Arabidopsis thaliana Crown Galls  . Issue 3 (29th September 2016)

• Record Type: Journal Article
• Authors: Deeken, Rosalia; Saupe, Stefanie; Klinkenberg, Joern; Riedel, Michael; Leide, Jana; Hedrich, Rainer; Mueller, Thomas D.
• Is Part Of: Plant physiology. Volume 172:Issue 3(2016)
• Page Start: 1911
• Page End: 1927
• Publication Date: 2016-09-29
• Subjects: Plant physiology -- Periodicals; Botany -- Periodicals; Periodicals; Electronic journals; 571.2
• DOI: 10.1104/pp.16.01486
• Languages: English
• ISSNs: 0032-0889

Abstract

Abstract : AtLtpI-4 involvement in suberin formation is essential for crown gall growth, while ectopic expression in epidermal cells provides evidence for AtLp-I-4 functioning in extracellular lipid deposition. Abstract: Nonspecific lipid transfer proteins reversibly bind different types of lipid molecules in a hydrophobic cavity. They facilitate phospholipid transfer between membranes in vitro, play a role in cuticle and possibly in suberin formation, and might be involved in plant pathogen defense signaling. This study focuses on the role of the lipid transfer protein AtLTPI-4 in crown gall development. Arabidopsis ( Arabidopsis thaliana ) crown gall tumors, which develop upon infection with the virulent Agrobacterium tumefaciens strain C58, highly expressed AtLTPI-4 . Crown galls of the atltpI-4 loss-of-function mutant were much smaller compared with those of wild-type plants. The gene expression pattern and localization of the protein to the plasma membrane pointed to a function of AtLTPI-4 in cell wall suberization. Since Arabidopsis crown galls are covered by a suberin-containing periderm instead of a cuticle, we analyzed the suberin composition of crown galls and found a reduction in the amounts of long-chain fatty acids (C18:0 ) in the atltpI-4 mutant. To demonstrate the impact of AtLtpI-4 on extracellular lipid composition, we expressed the protein in Arabidopsis epidermis cells. This led to a significant increase in the very-long-chain fatty acids C24 and C26 in the cuticular wax fraction. Homology modeling and lipid-protein-overlay assays showed that AtLtpI-4 protein can bind these very-long-chain fatty acids. Thus, AtLtpI-4 protein may facilitate the transfer of long-chain as well as very-long-chain fatty acids into the apoplast, depending on the cell type in which it is expressed. In crown galls, which endogenously express AtLtpI-4, it is involved in suberin formation.