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The A rabidopsis exocyst subunit SEC 3 A is essential for embryo development and accumulates in transient puncta at the plasma membrane
Author(s) -
Zhang Ying,
Immink Richard,
Liu ChunMing,
Emons Anne Mie,
Ketelaar Tijs
Publication year - 2013
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12236
Subject(s) - exocyst , microbiology and biotechnology , green fluorescent protein , biology , secretion , cytoplasm , exocytosis , protein subunit , brefeldin a , cell plate , subcellular localization , golgi apparatus , cell , cell division , cytokinesis , biochemistry , endoplasmic reticulum , gene
Summary The exocyst is a protein complex that is essential for polarized secretion in mammals and fungi. Although the exocyst is essential for plant development, its precise function has not been elucidated. We studied the role of exocyst subunit SEC 3 A in plant development and its subcellular localization. T ‐ DNA insertional mutants were identified and complemented with a SEC 3 A ‐green fluorescent protein ( GFP ) fusion construct. SEC 3 A ‐ GFP localization was determined using confocal microscopy. sec3a mutants are defective in the globular to heart stage transition in embryogenesis. SEC 3 A ‐ GFP has similar cell plate localization to the other plant exocyst subunits. In interphase cells, SEC 3 A ‐ GFP localizes to the cytoplasm and to the plasma membrane, where it forms immobile, punctate structures with discrete lifetimes of 2–40 s. These puncta are equally distributed over the cell surface of root epidermal cells and tip growing root hairs. The density of puncta does not decrease after growth termination of these cells, but decreases strongly when exocytosis is inhibited by treatment with brefeldin A . SEC 3 A does not appear to be involved in polarized secretion for cell expansion in tip growing root hairs. The landmark function performed by SEC 3 in mammals and yeast is likely to be conserved in plants.