The Small Heat Shock Proteins and Their Roles in Abiotic Stress Tolerance in Horticultural Plants

Abiotic stresses, such as extreme temperatures, salinity, drought, osmotic and oxidative stress are serious threats to horticulture and result in the deterioration of the environment. Plants have developed various mechanisms in response to adverse conditions, including the induction of small heat-shock proteins (sHSPs). sHSPs, encoded by nuclear genes and characterized by an alpha-crystallin domain, are known to be expressed in plants not only when the plants suffered high temperature stress but also in response to a wide range of other environmental challenges. sHSPs produced in plants function as molecular chaperones to bind to other proteins, stabilize unstable structures and promote the repair mechanism through refolding of proteins during and after exposure to stress, thereby playing a crucial role in plant stress response, resistance, tolerance and recovery. This paper summarizes the significance of sHSPs in abiotic stress responses in horticultural plants and incorporation of sHSPs in stress-tolerant horticultural plant breeding.