Abstract
Plant hormone brassinosteroids (BRs) are a group of polyhydroxylated steroids that play critical roles in regulating broad aspects of plant growth and development. The structural diversity of BRs is generated by the action of several groups of P450s. Brassinazole is a specific inhibitor of C-22 hydroxylase (CYP90B1) in BR biosynthesis, and the application use of brassinazole has emerged as an effective way of complementing BR-deficient mutants to elucidate the functions of BRs. In this article, we report a new triazole-type BR biosynthesis inhibitor, YCZ-18. Quantitative analysis the endogenous levels of BRs in Arabidopsis indicated that YCZ-18 significantly decreased the BR contents in plant tissues. Assessment of the binding affinity of YCZ-18to purified recombinant CYP90D1 indicated that YCZ-18 induced a typical type II binding spectrum with a Kd value of approximately 0.79 μM. Analysis of the mechanisms underlying the dwarf phenotype associated with YCZ-18 treatment of Arabidopsis indicated that the chemically induced dwarf phenotype was caused by a failure of cell elongation. Moreover, dissecting the effect of YCZ-18 on the induction or down regulation of genes responsive to BRs indicated that YCZ-18 regulated the expression of genes responsible for BRs deficiency in Arabidopsis. These findings indicate that YCZ-18 is a potent BR biosynthesis inhibitor and has a new target site, C23-hydroxylation in BR biosynthesis. Application of YCZ-18 will be a good starting point for further elucidation of the detailed mechanism of BR biosynthesis and its regulation.
Highlights
The oxidative metabolism of campesterol in plant tissues leads to the production of a group of bioactive polyhydroxylated steroids, collectively called brassinosteroids (BRs)
Wild-type Arabidopsis plants treated with 3 μM YCZ-18 displayed an approximately 90% reduction of hypocotyl length (Fig. 3A, third plant from the right), whereas those treated with Brz220 (3 μM) showed an approximately 80% reduction in hypocotyl length (Fig. 3A, second plant from the right)
To distinguish the primary site of action of YCZ-18 between BR biosynthesis and GA biosynthesis, we have previously shown that the dwarf phenotype of Arabidopsis seedlings induced with YCZ-18 in the dark could be rescued by the application of BR but not by GA [29]
Summary
The oxidative metabolism of campesterol in plant tissues leads to the production of a group of bioactive polyhydroxylated steroids, collectively called brassinosteroids (BRs). BRs are important plant hormones that play critical roles in regulating broad aspects of plant growth and development [1]. BRs act as essential regulators in cell elongation, cell division, and sex PLOS ONE | DOI:10.1371/journal.pone.0120812. Mutants with impaired BR synthesis display dramatic growth defects, such as decreased cell elongation, resulting in pleiotropic dwarf phenotypes, delayed flowering, and male sterility [4,5,6,7]. BRs modulate plant metabolic pathways in response to environmental biotic and abiotic stress resistance, including tolerance of salt, drought and oxidative stresses and pathogen resistance [8, 9]
Sign-in/Register to view highlights & summary 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.
