Update on Signal Transduction Regulation of the Heat-Shock Response

The heat-shock response is a conserved reaction of cells and organisms to elevated temperatures (heat shock or heat stress). Whereas severe heat stress leads to cellular damage and cell death, sublethal doses of heat stress induce a cellular response, the heat-shock response, which (a) protects cells and organisms from severe damage, (b) allows resumption of normal cellular and physiological activities, and (c) leads to a higher level of thermotolerance. Crucial to the survival of cells is the sensitivity of proteins and enzymes to heat inactivation and denaturation. Therefore, adaptive mechanisms exist that protect cells from the proteotoxic effects of heat stress. Owing to their sessile lifestyle, the acquisition of higher levels of environmental stress tolerance is of utmost importance to plants. It is not surprising that the heat-shock response is also linked to several other environmental stresses. Furthermore, an increasing number of studies indicate cross-protection between heat stress, dehydration/drought, cold/chilling/ freezing, heavy-metal stress, and oxidative stress in plants.