ABSTRACT
This chapter provides information on understanding the biosynthesis, metabolism, pathways and functions of brassinosteroids (BRs) and their possible role in fruit crops. BR is a group of plant steroid hormones, which regulate many processes in plant growth and development, including cell elongation, cell division, vascular differentiation, reproduction, rhizogenesis, flowering, fruit ripening, tolerance response to various biotic and abiotic stresses, and senescence. Naturally occuring BRs are polyhydroxylated steroidal hormones, which has a common 5a-cholestane skeleton. These steroidal components have been classified as C-27, C-28 or C-29 BRs based on the alkyl-substitutions in the side chain of brassinosteroids. Unlike other plant hormones, application of BRs in agriculture and horticulture, especially in fruit crops would not cause any residual effects on food, as these are reported to be nontoxic, non-genotoxic, biosafe, eco-friendly as well as natural synthesized in various plant parts. BRs regulate root meristem size and lateral root development in a concentration-dependent manner.
