Identification of a Chloroplast Dehydrin in Leaves of Mature Plants

Several types of proteins are known to accumulate as a result of dehydration stress in plants, and many of these are thought to serve a protective function. This includes the dehydrin family of proteins, which accumulate in cells in response to drought, low temperatures, or salinity and in embryo tissues during the maturation phase of seed development, when the seed is losing water in preparation for dormancy. Many studies to date have concentrated on the expression, localization, and function of dehydrins in seed tissues. Our study provides some of the first evidence for a chloroplast-localized dehydrin by using cell fractionation combined with immunofluorescence and immunogold electron microscopy to determine dehydrin location in mature leaf tissues of Pisum sativum and Zea mays. This article also documents constitutive expression of the chloroplast dehydrin as well as expression during different dehydrative stresses. The chloroplast-dehydrin expression pattern differs from most other dehydrins studied to date and suggests a role in basic cell metabolism for this particular dehydrin.