Wheat Responses and Tolerance to Terminal Heat Stress: A Review

Abstract

Supraoptimal temperatures and unpredictable fluctuations in global climate adversely affect plant growth and development resulting in a severe threat to wheat production. Although all the growth stages of wheat are sensitive to supraoptimal temperatures, the reproductive phase is the most sensitive one as it affects both grain setting and grain filling (GF). High temperature can alter biochemical, physiological, and morpho-anatomical behavior in wheat, which in turn affects its growth and development causing a reduction in pollen viability, duration of GF, and starch synthesis in the endosperm. At flowering, temperature above optimum results in seed sterility, while post-anthesis heat stress (HS) causes a reduction in starch biosynthesis and alters its composition. Wheat crop has evolved appropriate mechanisms such as escape, avoidance, and/or stay green to cope with HS. In addition, plants hasten the production of HS-related proteins such as heat shock proteins (HSPs) as their defense approach. An overview of wheat responses and tolerance to HS at biochemical, physiological, and morpho-anatomical behavior may help in formulating appropriate breeding strategies for wheat crop improvement.