The Heat Shock Response in Plants: Short-Term Heat Treatment Regimes and Thermotolerance

Abstract

The heat shock (HS) response is one of the most highly conserved biological systems known. It appears to be universal, having been observed in organisms ranging from eubacteria to archebacteria, from lower eukaryotes to plants and man. Almost every cell and tissue type including cultured cells of plants and animals undergo the HS response. The HS response is characterized by a number of interesting regulatory phenomena. Transcription of HS genes is rapidly activated and HS mRNAs accumulate to high levels. The initial transcriptional activation slows, and cessation of HS gene transcription occurs after about two hours of continuous HS. This shutdown of HS mRNA transcription under HS conditions has been referred to as self-regulation or autoregulation (DiDomenico et al., 1982; Key et al., 1983). There is also a rapid slowing of normal mRNA translation (Ashburner and Bonner, 1979; Key et al., 1981); the normal mRNAs persist during HS from near normal levels to much reduced levels depending upon the specific mRNA (Mirault et al., 1978; Key et al., 1985). Various aspects of the HS response have been recently reviewed for eukaryotes (Nover et al., 1984; Craig, 1985; Lindquist, 1986), for prokaryotes (Neidhardt et al., 1984) and for plants (Nagaoet al., 1986; Nagao and Key, 1988).