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Subcellular And Tissue Localization Of Dehydrins

Dehydrins may have multiple functions and are specialized for different growth conditions, tissues, cells and stresses. Their predominant localization in the plant vascular system and the apical meristems is crucial for plant growth and survival. Their accumulation in root tips may promote water influx into the actively dividing parenchymal cells of the root meristem. Similarly, in cells surrounding the xylem vessels, dehydrins may function as water attractants during the transport of water from xylem vessels to sink tissue.
Extensive localization studies revealed that dehydrins accumulate in specific tissues and cells in Arabidopsis under normal growth conditions. Immunohistochemical localization demonstrated tissue and cell type specificity in unstressed plants (Nylander et al., 2001). Arabidopsis dehydrins ERD14 and LTI29 were detected in the root tip of plants grown under normal conditions. ERD14, LTI29 and RAB18 are expressed in vascular tissues and RAB18 in stomatal guard cells. Accumulation of ERD14, LTI29 and RAB18 was detected in most cells upon stress treatment, most intensely in cells surrounding vascular tissues. Nylander et al. (2001) also found that dehydrin LTI30 was absent in unstressed plants, but accumulated upon stress treatment, mainly in vascular tissues and pollen sacks, probably being both transcriptionally and posttranscriptionally regulated.
Dehydrins have been associated with most cellular organelles, and post translational modifications, such as phosphorylation, can affect their localization. At the subcellular level dehydrins are localized in various cell compartments, such as the cytosol, nucleus, mitochondria, vacuole, and in the vicinity of the plasma membrane, but primarily in the cytosol and nucleus. The wheat dehydrin WCOR410, however, was found to accumulate preferentially in the vicinity of the plasma membrane of cells, in the vascular transition area (Danyluk et al., 1998). In some cases dehydrins are associated with cellular organelles. For example, peach PCA60, in addition to the cytosol and nucleus, is associated with chloroplasts (Wisniewski et al., 1999). Dehydrin-like proteins have been shown to be associated with mitochondria in winter wheat, winter rye and maize (Borovskii et al., 2000) and in cauliflower, Arabidopsis and yellow lupin plants submitted to cold stress (Rurek, 2010).


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