Analysis of the Golgi apparatus in Arabidopsis seed coat cells during polarized secretion of pectin-rich mucilage.
Differentiation of the Arabidopsis thaliana seed coat cells includes a secretory phase where large amounts of pectinaceous mucilage are deposited to a specific domain of the cell wall. During this phase, Golgi stacks had cisternae with swollen margins and trans-Golgi networks consisting of interconnected vesicular clusters. The proportion of Golgi stacks producing mucilage was determined by immunogold labeling and transmission electron microscopy using an antimucilage antibody, CCRC-M36. The large percentage of stacks found to contain mucilage supports a model where all Golgi stacks produce mucilage synchronously, rather than having a subset of specialist Golgi producing pectin product. Initiation of mucilage biosynthesis was also correlated with an increase in the number of Golgi stacks per cell. Interestingly, though the morphology of individual Golgi stacks was dependent on the volume of mucilage produced, the number was not, suggesting that proliferation of Golgi stacks is developmentally programmed. Mapping the position of mucilage-producing Golgi stacks within developing seed coat cells and live-cell imaging of cells labeled with a trans-Golgi marker showed that stacks were randomly distributed throughout the cytoplasm rather than clustered at the site of secretion. These data indicate that the destination of cargo has little effect on the location of the Golgi stack within the cell.
Young
Robin E
RE
Department of Botany, University of British Columbia, Vancouver, Canada V6T 1Z4.
McFarlane
Heather E
HE
Hahn
Michael G
MG
Western
Tamara L
TL
Haughn
George W
GW
Samuels
A Lacey
AL
D000269:Adhesives / Q000737:chemistry / Q000378:metabolism*; D017360:Arabidopsis / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D002454:Cell Differentiation; D018506:Gene Expression Regulation, Plant; D006056:Golgi Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D010368:Pectins / Q000378:metabolism; D012639:Seeds / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure
D000269:Adhesives; D010368:Pectins