Crosstalk between brassinosteroid signaling, ROS signaling and phenylpropanoid pathway during abiotic stress in plants: Does it exist?

Numerous studies have highlighted the BR (brassinosteroid) induced stress tolerance to different environmental cues. Increased free radicals and other oxidative species are produced in plant system by various environmental stresses such as high, low temperature, drought stress, light stress, pathogen infection and nutrient deficiency. The main approach followed by a plant system to overcome this stress is, either use primary metabolites and/or engaging secondary metabolites. The ROS (reactive oxygen species) neutralization is achieved by intricate antioxidant system developed by the plant cell. The primary metabolite stress tolerance is achieved mostly through classical antioxidant system viz ascorbate peroxidase, superoxide dismutase, catalase, glutathione reductase and monodehydroascorbate reductase, the low molecular weight antioxidants ascorbate and glutathione. On the other hand, the second level of defence is achieved by employing diverse secondary metabolites like lignins, tannins, flavonoids, stilbenes, hydroxycinnamate esters, phenolics synthesized in plants, thereby, playing great role in ROS scavenging. In this review we analyze the multifaceted role of BR signaling in various abiotic stresses and its potential crosstalk with other ROS signaling and phenylpropanoid pathway.