Molecular mechanisms of heat shock proteins and thermotolerance in plants

Abstract

Plants are sessile organisms which are regularly exposed to many stresses due to changing environmental factors. The majority of the stresses induce the production of a group of proteins called heat shock proteins (Hsps). These proteins are grouped into different classes according to their molecular weight: Hsp100, Hsp90, Hsp70, Hsp60, small heat shock proteins (sHsps), and ubiquitins. Hsps act as molecular chaperones and regulate the protein folding, accumulation and transportation, and removal of damaged proteins. In case of temperature stress signaling pathway, the plasma membrane carries out the primary role with the help of other secondary messengers, such as Ca2+ ions, hydrogen peroxide (H2O2), and nitric oxide (NO). Other components, such as mitogen-activated protein kinases (MAPK) and calmodulins, regulate the activation of heat shock transcription factors (HSFs) and thus the synthesis of Hsps. In this chapter, we discuss the significance of Hsps in thermotolerance and also the role of different classes of Hsps and their interactions with other stress-induced components.