BIOLOGIA PLANTARUM 51 (4): 601-617, 2007 601 REVIEW The role of dehydrins in plant response to cold K. KOSOVÁ* , ** ,1 , P. VÍTÁMVÁS*and I.T. PRÁŠIL* Research Institute of Crop Production, Drnovská 507, Prague, CZ-16106, Czech Republic* Faculty of Science, Charles University, Vini ná 5, Prague, CZ-12844, Czech Republic** Abstract Dehydrins present a distinct biochemical group of late embryogenesis abundant (LEA) proteins characterised by the presence of a lysine-rich amino acid motif, the K-segment. They are highly hydrophilic, soluble upon boiling, and rich in glycine and polar amino acids. It is proposed that they can act as emulsifiers or chaperones in the cells, i.e., they protect proteins and membranes against unfavourable structural changes caused by dehydration. Cold usually precedes freezing in nature and induces many physiological and biochemical changes in the cells of freezing-tolerant plant species (cold-acclimation) that enable them to survive unfavourable conditions. It is demonstrated that the induction of dehydrin expression and their accumulation is an important part of this process in many dicotyledons (both herbaceous and woody species), and also in winter cultivars of cereals, especially wheat and barley. Some mechanisms which are proposed to be involved in regulation of dehydrin expression are discussed, i.e., endogenous content of abscisic acid, homologues of Arabidopsis C-repeat binding factor (CBF) transcriptional activators, the activity of vernalization genes and photoperiodic signals. Finally, we outline some new approaches emerging for the solution of the complex mechanisms involved in plant cold-acclimation, especially the methods of functional genomics that enable to observe simultaneously changes in the activity of many genes and proteins in a single sample. Additional key words: abscisic acid, cereals, cold-acclimation, dicotyledons, frost resistance, K-segment, LEA D-11 proteins, low temperature stress. Introduction Dehydrins, also known as LEA D-11 or LEA II (late embryogenesis abundant) proteins, are proteins whose expression is induced by various environmental factors, which cause dehydration of the cells. Among these factors, cold, frost, heat, drought, salinity, and enhanced evaporation are the most notable (e.g., Wisniewski et al. 1996, Buchanan et al. 2005, Rampino et al. 2006, Wahid and Close 2007). Expression of many dehydrins is also induced by increased abscisic acid (ABA) content. The classification of LEA proteins originates from sequence homologies of late embryo-genesis abundant proteins from cotton to LEA proteins from other plant species. Currently, LEA proteins are divided into 5 groups: LEA D19 (group I), LEA D11 (group II, also termed dehydrins), LEA D7 (group III), LEA D113 (group IV), and LEA D95 (group V) (Ingram and Bartels 1996). Currently, dehydrins are considered all the proteins which have at least one copy of the lysine-rich amino acid Received 26 September 2006, accepted 16 February 2007. Abbreviations: ABA - abscisic acid; ABRE - ABA-responsive element; bZIP - basic-domain leucine zipper; CaMV - cauliflower mosaic virus; CAT - catalase; CBF - C-repeat-binding factor; Cor - cold-regulated; CRT - C-repeat; Dhn - dehydrin; DRE - dehydration-responsive element; ELIPs - early light-inducible proteins; Erd - early response to drought; EST - expressed sequence tag; Fr gene - frost resistance gene; FT - frost tolerance; GUS - -glucuronidase; LEA - late embryogenesis abundant; LD - long day; LDH - lactate dehydrogenase; LT - low temperature; LT 50 - lethal temperature when 50 % samples die; Lti - low temperature-induced; LTRE - low temperature-responsive element; M r - relative molecular mass; NLS - nuclear localisation sequence; PD 50 - 50 % protein denaturation; pI - isoelectric point; Ppd - photoperiod; QTL - quantitative trait loci; Rab - response to ABA; RT-PCR - reverse transcriptase polymerase chain reaction; SD - short day; SDS-PAGE - sodium dodecyl sulphate polyacrylamide gel electrophoresis; UV CD - ultra-violet circular dichroism; Vrn - vernalization; Wcor - wheat cold-regulated; Wcs - wheat cold-specific; Wdhn - wheat dehydrin; WT - wild type; 2DE - two dimensional electrophoresis; 2D-DIGE - two dimensional difference gel electrophoresis. Acknowledgement: This work was supported by the Grants MZE 0002700602 and GA R 206/03/H137. The authors thank Doc. I. Tichá (Department of Plant Physiology, Charles University in Prague) for reading and helpful suggestions of the manuscript. 1 Author for correspondence; fax: (+420) 233310636, e-mail: kosova@vurv.cz