Methyl Jasmonate and Brassinosteroids: Emerging Plant Growth Regulators in Plant Abiotic Stress Tolerance and Environmental Changes

Any extrinsic agent that exerts a negative effect on plants’ physiology is usually defined as stress. Crop plants in a given habitat encounter myriads of non-biotic pressures such as high light intensity, salt, metal/metalloid, heat, drought, and/or ultraviolet or a combination of these stresses and biotic ones such as pathogens, weeds, and insect predation. In a natural environment, plants encounter these stresses simultaneously and respond and adapt to these environmental pressures by the regulatory circuitry networks involving various growth regulating signaling molecules. Stress induces too much production of reactive oxygen species (ROS). In order to acclimate/adapt to stress conditions, in current times, plants’ acclamatory and defense responses are being regulated by various exogenous phytoprotectants such as supplements of exogenous plant growth regulators (PGRs) that mediate the redox balance under dynamic environment. The use of exogenous PRGs to impart abiotic stress tolerance is an emerging and burgeoning topic. PGRs are signaling elicitors that regulate growth and development under optimal and stress conditions. However, the critical tolerance trade-off of methyl jasmonate (MeJ) and brassinosteroids (BRs) in inducing abiotic stress tolerance has received little attention. Therefore, in this present chapter, we present the role of these two selected PGRs and their crosstalk with other signaling molecules in improving abiotic stress in different crop plants.