Two-dimensional Gel Analysis of 45 ku Heat Shock Proteins from a Drought and Heat Resistant Maize Line

Abstract

Summary In a previous study, Ristic et al. (1991) described a band of heat-shock protein(s) [HSP(s)] of 45 ku (kDa) in the leaf tissue of a drought and heat resistant maize line, ZPBL 1304. This band had not been previously described in the leaves of maize and does not appear to be common in higher plants. It was not known how many polypeptides comprised this 45 ku band, and whether drought stress can induce the synthesis of proteins of 45 ku. The objectives of this study were two fold: 1) to analyze the 45 ku HSP band from leaf tissue of the ZPBL 1304 line using two-dimensional gel electrophoresis (heat-shock polypeptide study), and 2) to investigate the possible synthesis of 45 ku protein(s) in ZPBL 1304 line under dry conditions. For heat-shock polypeptide study, plants were exposed to two environmental stress treatments: soil drying and high temperature (45 °C) and high temperature alone (45 °C). Generally, the pattern of heat shock (HS) polypeptide synthesis under soil drying and high-temperature conditions was similar to that under high temperature conditions. Two dimensional gel electrophoresis revealed three HS polypeptides of 45 ku with isoelectric points (p/) ranging from 5.0 to 5.5 and two HS polypeptides of 46 ku with p/slightly above 5.5. Drought stress alone did not induce the synthesis of proteins of 45 ku. The possible role of the 45/46 ku HSPs in the development of heat resistance is discussed.