title: F-actin-dependent endocytosis of cell wall pectins in meristematic root cells. Insights from brefeldin A-induced compartments.
abstract: Brefeldin A (BFA) inhibits exocytosis but allows endocytosis, making it a valuable agent to identify molecules that recycle at cell peripheries. In plants, formation of large intracellular compartments in response to BFA treatment is a unique feature of some, but not all, cells. Here, we have analyzed assembly and distribution of BFA compartments in development- and tissue-specific contexts of growing maize (Zea mays) root apices. Surprisingly, these unique compartments formed only in meristematic cells of the root body. On the other hand, BFA compartments were absent from secretory cells of root cap periphery, metaxylem cells, and most elongating cells, all of which are active in exocytosis. We report that cell wall pectin epitopes counting rhamnogalacturonan II dimers cross-linked by borate diol diester, partially esterified (up to 40%) homogalacturonan pectins, and (1-->4)-beta-D-galactan side chains of rhamnogalacturonan I were internalized into BFA compartments. In contrast, Golgi-derived secretory (esterified up to 80%) homogalacturonan pectins localized to the cytoplasm in control cells and did not accumulate within characteristic BFA compartments. Latrunculin B-mediated depolymerization of F-actin inhibited internalization and accumulation of cell wall pectins within intracellular BFA compartments. Importantly, cold treatment and protoplasting prevented internalization of wall pectins into root cells upon BFA treatment. These observations suggest that cell wall pectins of meristematic maize root cells undergo rapid endocytosis in an F-actin-dependent manner.
authors.affiliation: Plant Cell Biology, Institute of Botany, University of Bonn, Kirschallee 1, D-53115 Bonn, Germany. baluska@uni-bonn.de
authors.forename: Frantisek
authors.initials: F
authors.lastname: Baluska
authors.forename: Andrej
authors.initials: A
authors.lastname: Hlavacka
authors.forename: Jozef
authors.initials: J
authors.lastname: Samaj
authors.forename: Klaus
authors.initials: K
authors.lastname: Palme
authors.forename: David G
authors.initials: DG
authors.lastname: Robinson
authors.forename: Toru
authors.initials: T
authors.lastname: Matoh
authors.forename: David W
authors.initials: DW
authors.lastname: McCurdy
authors.forename: Diedrik
authors.initials: D
authors.lastname: Menzel
authors.forename: Dieter
authors.initials: D
authors.lastname: Volkmann
mesh_terms: D020823:ADP-Ribosylation Factor 1 / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D015415:Biomarkers; D020126:Brefeldin A / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism*; D002478:Cells, Cultured; D003080:Cold Temperature; D004705:Endocytosis / Q000187:drug effects*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism; D000939:Epitopes; D005875:Gibberellins / Q000378:metabolism; D018519:Meristem / Q000166:cytology / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D010368:Pectins / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology / Q000378:metabolism; D011523:Protoplasts / Q000378:metabolism; D003313:Zea mays / Q000187:drug effects / Q000378:metabolism; D021601:trans-Golgi Network / Q000378:metabolism
chemical_list: D000199:Actins; D015415:Biomarkers; D000939:Epitopes; D005875:Gibberellins; D020126:Brefeldin A; D010368:Pectins; D020823:ADP-Ribosylation Factor 1