Abstract
Steroid hormones are important signaling molecules in plants and animals. The plant steroid hormone brassinosteroids were first isolated and characterized in the 1970s and have been studied since then for their functions in plant growth. Treatment of plants or plant cells with brassinosteroids revealed they play important roles during diverse developmental processes, including control of cell expansion, cell division, and vascular differentiation. Molecular genetic studies, primarily in Arabidopsis thaliana, but increasingly in many other plants, have identified many genes involved in brassinosteroid biosynthesis and responses. Here we review the roles of brassinosteroids in cell expansion, cell division, and vascular differentiation, comparing the early physiological studies with more recent results of the analysis of mutants in brassinosteroid biosynthesis and signaling genes. A few representative examples of other molecular pathways that share developmental roles with brassinosteroids are described, including pathways that share functional overlap or response components with the brassinosteroid pathway. We conclude by briefly discussing the origin and conservation of brassinosteroid signaling.
Highlights
Brassinosteroids (BRs) are an essential plant hormone and are considered at the same level as the classic plant hormones auxin, cytokinin, ethylene, gibberellic acid, and abscisic acid. This is due to the important roles of BRs in regulating developmental processes controlled by the classic plant hormones such as cell expansion, cell division, and differentiation, and because of the well-characterized biosynthesis and signaling pathways of BRs
These results indicated that 1) cell expansion in two dimensions was affected in leaf cells, and that 2) other differences significantly impact the growth of these BR-deficient mutants
The hypothesis that BRs function in phloem differentiation was confirmed by more recent studies from [71], who analyzed the differentiation of the protophloem in bri1 and bri1; brl1; brl3 triple mutants and found that gaps in normally continuous cells of the phloem could be identified in just the triple mutants
Summary
Brassinosteroids (BRs) are an essential plant hormone and are considered at the same level as the classic plant hormones auxin, cytokinin, ethylene, gibberellic acid, and abscisic acid This is due to the important roles of BRs in regulating developmental processes controlled by the classic plant hormones such as cell expansion, cell division, and differentiation, and because of the well-characterized biosynthesis and signaling pathways of BRs. In this review, we take a historical perspective and begin by describing the initial chemical characterization of plant steroid hormones and their bioactivity in different plant-based assays for cell elongation, cell division, and vascular development. Many investigators did not clearly distinguish between cell expansion and cell division or determine if both were affected to the same degree in their assays
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
