title: In vivo analysis of the calcium signature in the plant Golgi apparatus reveals unique dynamics.
abstract: The Golgi apparatus is thought to play a role in calcium homeostasis in plant cells. However, the calcium dynamics in this organelle is unknown in plants. To monitor the [Ca2+]Golgiin vivo, we obtained and analyzed Arabidopsis thaliana plants that express aequorin in the Golgi. Our results show that free [Ca2+] levels in the Golgi are higher than in the cytosol (0.70 μM vs. 0.05 μM, respectively). Stimuli such as cold shock, mechanical stimulation and hyperosmotic stress, led to a transient increase in cytosolic calcium; however, no instant change in the [Ca2+]Golgi concentration was detected. Nevertheless, a delayed increase in the [Ca2+]Golgi up to 2-3 μM was observed. Cyclopiazonic acid and thapsigargin inhibited the stimuli-induced [Ca2+]Golgi increase, suggesting that [Ca2+]Golgi levels are dependent upon the activity of Ca2+-ATPases. Treatment of these plants with the synthetic auxin analog, 2,4-dichlorophenoxy acetic acid (2,4-D), produced a slow decrease of free calcium in the organelle. Our results indicate that the plant Golgi apparatus is not involved in the generation of cytosolic calcium transients and exhibits its own dynamics modulated in part by the activity of Ca2+ pumps and hormones.
authors: Calcium Signalling Research Unit, Metallomics-Chile Corporation, La Serena, Chile.
authors: Viviana R
authors: VR
authors: Ordenes
authors: Ignacio
authors: I
authors: Moreno
authors: Daniel
authors: D
authors: Maturana
authors: Lorena
authors: L
authors: Norambuena
authors: Anthony J
authors: AJ
authors: Trewavas
authors: Ariel
authors: A
authors: Orellana
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000737:chemistry / Q000494:pharmacology; D000331:Aequorin / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000235:genetics; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism*; D006056:Golgi Apparatus / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000737:chemistry; D007211:Indoles / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000737:chemistry / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D007210:Indoleacetic Acids; D007211:Indoles; D010937:Plant Growth Regulators; D015084:2,4-Dichlorophenoxyacetic Acid; D000331:Aequorin; D019284:Thapsigargin; D000252:Calcium-Transporting ATPases; D002118:Calcium; C000543:cyclopiazonic acid