Induction of plants resistance to influence of abiotic stressors by exogenous brassinosteroids

Abstract

Brassinosteroids (BS) are the class of plant polyhydroxysteroids structurally related to steroid hormones of vertebrates and insects. They play a key role in the maintaining of normal plant growth both under the optimal conditions and under the influence of unfavorable environmental factors. BS bind to specific receptors and mediate their action through the cascade of signal transduction, which ultimately entails the change in the expression of thousands of nuclear genes involved in the regulation of various functions of the plant organism. In addition to specific proteins, universal signaling mediators of non-protein nature, such as calcium ions, reactive oxygen species, nitric oxide (NO), hydrogen sulfide (H2S), as well as components of lipid signaling, are involved in the transduction of BS signals. BS exert the protective effect on plants under the influence of unfavorable factors of various natures – hypo- and hyperthermia, drought, salinity, heavy metals, etc. The wide range of BS effects is probably associated with their ability to regulate the expression of key genes involved in the ensuring of plant resistance: genes encoding the transcription factors MYB/MYC, genes of family of proteins WRKY and COR, dehydrins, heat shock proteins, cytoskeletal proteins, and antioxidant enzymes. The functioning of these genes determines the implementation of plant adaptation programs to stressors of various natures. Also, the change in the BS content in plants causes the change in their hormonal status in general. The review analyzes the data on the specific protective effects of BS and genes regulated by them, involved in adaptation to certain stress factors, summarizes the information on the physiological effects of new synthetic conjugates of BS with other phytohormones, in particular with salicylic acid. It is noted that the modification of signaling pathway of BS can be one of the strategic directions for solving the problem of adaptation of cultivated plants.