title: Effect of drought and rewatering on the cellular status and antioxidant response of Medicago truncatula plants.
abstract: Effects of water stress on plants have been well-documented. However, the combined responses to drought and rewatering and their underlying mechanisms are relatively unknown. The present study attempts to describe spatiotemporal alterations in the physiology and cellular status of Medicago truncatula tissues that result from and subsequently follow a period of moderate water deficit. Physiological processes and cellular damage levels were monitored in roots and leaves by determining lipid peroxidation levels, as well as nitric oxide and hydrogen peroxide content, further supported by stomatal conductance and chlorophyll fluorescence measurements in leaves. During water stress, cells in both organs displayed increased damage levels and reactive oxygen and nitrogen species content, while leaves showed reduced stomatal conductance. Furthermore, both tissues demonstrated increased proline content. Upon rewatering, plants recovered displaying readings similar to pre-stress control conditions. Furthermore, molecular analysis of antioxidant gene expression by quantitative real-time RT-PCR revealed differential spatiotemporal regulation in a number of genes examined (including catalase, cytosolic ascorbate peroxidase, copper/zinc and iron superoxide dismutase and alternative oxidase). Overall, M. truncatula plants demonstrated increased sensitivity to drought-induced oxidative damage; however, this was reversed following rewatering indicating a great elasticity in the plant's capacity to cope with free oxygen radicals.
authors.affiliation: Department of Agricultural Sciences, Biotechnology and Food Science, Cyprus University of Technology, Limassol, Cyprus.
authors.forename: Panagiota
authors.initials: P
authors.lastname: Filippou
authors.forename: Chrystalla
authors.initials: C
authors.lastname: Antoniou
authors.forename: Vasileios
authors.initials: V
authors.lastname: Fotopoulos
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D055864:Droughts; D018506:Gene Expression Regulation, Plant; D006861:Hydrogen Peroxide / Q000378:metabolism; D015227:Lipid Peroxidation; D046913:Medicago truncatula / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress; D018515:Plant Leaves / Q000166:cytology / Q000502:physiology; D018517:Plant Roots / Q000166:cytology / Q000502:physiology; D026361:Reactive Nitrogen Species / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D014867:Water / Q000502:physiology
chemical_list: D000975:Antioxidants; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D014867:Water; D009569:Nitric Oxide; D006861:Hydrogen Peroxide