ACCUMULATION OF AN ACIDIC DEHYDRIN IN THE VICINITY OF THE PLASMA-MEMBRANE DURING COLD-ACCLIMATION OF WHEAT

Expression of the acidic dehydrin gene wcor410 was found to be associa ted with the development of freezing tolerance in several Gramineae sp ecies, This gene is part of a family of three homologous members, wcor 410, wcor410b, and wcor410c, that have been mapped to the long arms of the homologous group 6 chromosomes of hexaploid wheat, To gain insigh t into the function of this gene family, antibodies were raised agains t the WCOR410 protein and affinity purified to eliminate cross-reactiv ity with the WCS120 dehydrin-like protein of wheat, Protein gel blot a nalyses showed that the accumulation of WCOR410 proteins correlates we ll with the capacity of each cultivar to cold acclimate and develop fr eezing tolerance, Immunoelectron microscope analyses revealed that the se proteins accumulate in the vicinity of the plasma membrane of cells in the sensitive vascular transition area where freeze-induced dehydr ation is likely to be more severe, Biochemical fractionation experimen ts 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 prop erties, abundance, and localization of these proteins suggest that the y are involved in the cryoprotection of the plasma membrane against fr eezing or dehydration stress. We propose that WCOR410 plays a role in preventing the destabilization of the plasma membrane that occurs duri ng dehydrative conditions.