The thiol compounds glutathione and homoglutathione differentially affect cell development in alfalfa (Medicago sativa L.).
Glutathione (GSH) is an important scavenger of Reactive Oxygen Species (ROS), precursor of metal chelating phytochelatins, xenobiotic defence compound and regulator of cell proliferation. Homoglutathione (hGSH) is a GSH homologue that is present in several taxa in the family of Fabaceae. It is thought that hGSH performs many of the stress-defence roles typically ascribed to GSH, yet little is known about the potential involvement of hGSH in controlling cell proliferation. Here we show that hGSH/GSH ratios vary across organs and cells and that these changes in hGSH/GSH ratio occur during dedifferentiation and/or cell cycle activation events. The use of a GSH/hGSH biosynthesis inhibitor resulted in impaired cytokinesis in isolated protoplasts, showing the critical importance of these thiol-compounds for cell division. However, exposure of isolated protoplasts to exogenous GSH accelerated cytokinesis, while exogenous hGSH was found to inhibit the same process. We conclude that GSH and hGSH have distinct functional roles in cell cycle regulation in Medicago sativa L. GSH is associated with meristemic cells, and promotes cell cycle activation and induction of somatic embryogenesis, while hGSH is associated with differentiated cells and embryo proliferation.
Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium; Institute of Biology II/Molecular Plant Physiology, Albert-Ludwigs-Universität Freiburg, Schänzlestr. 1, 79104 Freiburg, Germany. Electronic address: taras.pasternak@biologie.uni-freiburg.de.
Taras
T
Pasternak
Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. Electronic address: han.asard@ua.ac.be.
Han
H
Asard
Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium; Antwerp Maritime Academy, Noordkasteel Oost 6, B-2030 Antwerp, Belgium. Electronic address: geert.potters@hzs.be.
Geert
G
Potters
Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium; School of Biological, Earth and Environmental Sciences, University College Cork, Distillery Field, North Mall, Cork, Ireland. Electronic address: m.jansen@ucc.ie.
Marcel A K
MA
Jansen
D005978:Glutathione / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D000455:Medicago sativa / Q000166:cytology*; D008970:Molecular Weight; D018515:Plant Leaves / Q000378:metabolism
C402172:homoglutathione; D005978:Glutathione
2,4-D; 2,4-dichlorophenoxyacetic acid; 4′,6-diamidino-2-phenylindole; ASC; Alfalfa; BSO; Cell differentiation; Cytokinesis; DAPI; GSH; GSHS; Glutathione; Homoglutathione; Medicago; RT-PCR; ascorbate; glutathione; glutathione synthetase; hGSH; hGSHS; homoglutathione; homoglutathione synthetase; l-buthionine sulfoximine; reverse transcriptase polymerase chain reaction