TISSUE-TYPE-SPECIFIC HEAT-SHOCK RESPONSE AND IMMUNOLOCALIZATION OF CLASS-I LOW-MOLECULAR-WEIGHT HEAT-SHOCK PROTEINS IN SOYBEAN

A monospecific polyclonal antibody was used to study the tissue-type s pecificity and intracellular localization of class I low-molecular-wei ght (LMW) heat-shock proteins (HSPs) in soybean (Glycine max) under di fferent heat-shock regimes. In etiolated soybean seedlings, the root m eristematic regions contained the highest levels of LMW HSP. No tissue -type-specific expression of class I LMW HSP was detected using the ti ssue-printing method. In immunolocalization studies of seedlings treat ed with HS (40 degrees C for 2h) the class 1 LMW HSPs were found in th e aggregated granular structures, which were distributed randomly in t he cytoplasm and in the nucleus. When the heat shock was released, the granular structures disappeared and the class I LMW HSPs became distr ibuted homogeneously in the cytoplasm. When the seedlings were then gi ven a more severe heat shock following the initial 40 degrees C --> 28 degrees C treatment, a large proportion of the class I LMW HSPs that originally localized in the cytoplasm were translocated into the nucle us and nucleolus. Class I LMW HSPs may assist in the resolubilization of proteins denatured or aggregated by heat and may also participate i n the restoration of organellar function after heat shock.