Synthesis and Properties of Brassinosteroid Biosynthesis Inhibitor Fluorescent Probe with Dansyl Moiety

Brassinosteroids (BRs) are important plant hormones that play key roles in plant development and defense responses to environmental cues. To explore the inhibition mechanism of BR biosynthesis, we report the synthesis of novel triazole derivatives with dansyl moiety (YCZ-FD) as a fluorescent probe. Inhibition of YCZ-FDs against BR biosynthesis was investigated by an assay method using Arabidopsis grown in the darkness. We found that YCZ-FD1 displays highly fluorescent intensity. The maximum excitation and emission wavelengths were found at 326 and 542 nm, respectively. YCZ-FD1 inhibits the stem elongation of Arabidopsis seedlings with an IC50 value approximately 19.8 ± 1.1 µM. To verifythe primary sites of action of YCZ-FDs on the biosynthesis of GA and BRs, effects of coapplication of GA3 (1µM) and/or brassinolide (BL, 10 nM) on YCZ-FD1 treated Arabidopsis seedlings were investigated. We found that co-application of BL reversed the YCZ-FD1 induced dwarfism of Arabidopsis seedlings while GA did not. Keywords: Azole derivatives, biosynthesis inhibitor, brassinosteroid, dansyl derivatives, fluorescent probe, plant hormone.