Plants growing in natural environments encounter various biotic and abiotic stresses during all periods of their growth and development. Biotic stresses such as pests and pathogens and abiotic stresses such as high temperature, low temperature, high light (photo-oxidative), drought, nutrient and salt stresses, are the primary causes of crop yield and quality reductions. High temperature or heat stress can lead to retardation in plant growth and development, and even death. It causes protein dysfunction/damage and alters the cellular proteome, and it can lead to the accumulation of toxic protein aggregates. Plants, as well as other organisms, respond to heat stress by inducing heat-shock proteins (Hsps) for self-defense. Thermotolerance in plants is related to the expression of Hsps (Vierling, 1991). Among major Hsps, there are highly conserved proteins in living organisms, namely ‘molecular chaperones.’ They are expressed under normal and various stress conditions. They play an important role in the maintenance of protein homeostasis in cells.