Accumulation of an Acidic Dehydrin in the Vicinity of the Plasma Membrane during Cold Acclimation of Wheat

Abstract

Expression of the acidic dehydrin gene wcor410 was found to be associated with the development of freezing tolerance in several Gramineae species. This gene is part of a family of three homologous members, wcor410, wcor410b, and wcor410c, that have been mapped to the long arms of the homologous group 6 chromosomes of hexaploid wheat. To gain insight into the function of this gene family, antibodies were raised against the WCOR410 protein and affinity purified to eliminate cross-reactivity with the WCS120 dehydrin-like protein of wheat. Protein gel blot analyses showed that the accumulation of WCOR410 proteins correlates well with the capacity of each cultivar to cold acclimate and develop freezing tolerance. Immunoelectron microscope analyses revealed that these proteins accumulate in the vicinity of the plasma membrane of cells in the sensitive vascular transition area where freeze-induced dehydration is likely to be more severe. Biochemical fractionation experiments indicated that WCOR410 is a peripheral protein and not an integral membrane protein. These results provide direct evidence that a subtype of the dehydrin family accumulates near the plasma membrane. The properties, abundance, and localization of these proteins suggest that they are involved in the cryoprotection of the plasma membrane against freezing or dehydration stress. We propose that WCOR410 plays a role in preventing the destabilization of the plasma membrane that occurs during dehydrative conditions.

Genetic approaches towards overcoming water deficit in plants - special emphasis on LEAs

“…The DHNs are characterized by the conserved sequences Y, S and K segments and have been further classified based on sequence homology (see Structure and functional studies of DHNs). Localization of specific dehydrins at the plasma membrane (Danyluk et al 1998) and also on the endomembranes (Dure, 1993) is consistent with their role in stabilizing cellular structures during dehydration stress (Kazuoka and Oeda, 1994;Close, 1997;Nylander et al, 2001). Dehydrin-like proteins (DLPS) are known to accumulate in organelles such as mitochondria of Triticum aestivum, Secale cereale and in also in Zea mays in response to drought, freezing, cold, and exogenous ABA treatment (Borovskii et al, 2002).…”

“…DHNs localize primarily to the nucleus or cytoplasm (Houde et al, 1995;Bracale et al, 1997), but studies also corroborate their presence either in the plasma membrane (Danyluk et al, 1998), endoplasmic reticulum (Neven et al, 1993), chloroplast (Wisniewski et al, 1999), mitochondria (Borovskii et al, 2002) or even in the vacuole (Heyen et al, 2002). DHNs may thus be expressed either constitutively [e.g.…”

“…Arabidopsis DHNX] or confined to the root tip (ERD14 and LTI29), vascular tissues (ERD14, LTI29 and RAB18) and stomatal guard cells (RAB18). DHNs accumulate within vascular tissues (Godoy et al, 1994;Houde et al, 1995;Danyluk et al, 1998;Nylander et al, 2001), pollen sacs, guard cells and root meristems (Nylander et al, 2001), endosperm and zygotic embryos of mature seeds, developing root primordia (Godoy et al, 1994;Bracale et al, 1997), wheat crown tissues (Houde et al, 1995) and peach shoots (Wisniewski et al, 1999). DHNs found only in the cytosol include those of C. plantagineum DSP16 (Schneider et al, 1993) and rice RAB21 (Mundy and Chua, 1988).…”

Cold responsive EARLI1 type HyPRPs improve freezing survival of yeast cells and form higher order complexes in plants

“…Unless otherwise stated, for immunoblot analyses using anti-EARLI1 antibodies, the reducing agent β-mercaptoethanol (Sigma) was omitted from the loading buffer. Total plant protein was isolated in Laemmli buffer from frozen plant tissue ground to a fine powder and quantified by the Bio-Rad Dc Protein Assay (BioRad), as described previously (Danyluk et al 1998). Protoplasts used for protein isolation were prepared from 20 rosette leaves of 3-week-old Col-0 wild type plants before or after 3 d of cold treatment as described previously (http://www.genetics.mgh.harvard.edu/sheenweb).…”

“…Mean survival rates ± SE are shown for 3-6 different experiments (At4g12470, n = 3; At4g12480 = EARLI1, n = 6; At4g12490, n = 5; At4g12500, n = 6). Significantly different treatment means (P < 0.05, paired Student's t test) are indicated with the star sign (*) Proteins were quantified for equal loading using a detergent compatible protein assay (Danyluk et al 1998). Proteins were separated by SDS-PAGE and probed with anti-EARLI1 antiserum.…”