Role of brassinosteroids in mitigating abiotic stresses in plants

Plants require extrinsic factors like air, water, light, nutrition, etc. for the regulation of their growth and development. Similarly, phytohormones are equally important for plants as intrinsic factors. Phytohormones are active molecules vital for various aspects in growth and development starting from embryogenesis, plant-pathogen defense and organ size regulation to reproductive development. These hormones also play an active role in mediating defense response against biotic and abiotic stresses in plants. According to estimates, a substantial loss in agricultural yields leading to concerns on food security worldwide has been reported due to abiotic stresses like salinity, extreme temperatures, drought, etc. To cope up with harsh stress conditions, plants develop certain altered growth patterns and physiological processes. Among various groups of phytohormones produced by plants, those which are based on isoprenoid origin are quite important in safeguarding plants against environmental stress. Brassinosteroids are one of the novel groups of plant hormones of isoprenoid origin. Due to its remarkable growth supporting property, these are regarded as phytohormones with pleiotropic effects. They dominate miscellaneous physiological activities such as growth, development, rhizogenesis, seed germination, senescence and most importantly abiotic stress tolerance in plants. In general, when a plant perceives a signal produced by stress, then it triggers a cascade mechanism of signal transduction with plant growth regulators, acting as alphatransducers.