Brassinolide Enhances the Level of Brassinosteroids, Protein, Pigments, and Monosaccharides in Wolffia arrhiza Treated with Brassinazole

Brassinolide (BL) represents brassinosteroids (BRs)-a group of phytohormones that are essential for plant growth and development. Brassinazole (Brz) is as a synthetic inhibitor of BRs' biosynthesis. In the present study, the responses of Wolffia arrhiza to the treatment with BL, Brz, and the combination of BL with Brz were analyzed. The analysis of BRs and Brz was performed using LC-MS/MS. The photosynthetic pigments (chlorophylls, carotenes, and xanthophylls) levels were determined using HPLC, but protein and monosaccharides level using spectrophotometric methods. The obtained results indicated that BL and Brz influence W. arrhiza cultures in a concentration-dependent manner. The most stimulatory effects on the growth, level of BRs (BL, 24-epibrassinolide, 28-homobrassinolide, 28-norbrassinolide, catasterone, castasterone, 24-epicastasterone, typhasterol, and 6-deoxytyphasterol), and the content of pigments, protein, and monosaccharides, were observed in plants treated with 0.1 mu MBL. Whereas the application of 1 mu M and 10 mu MBrz caused a significant decrease in duckweed weight and level of targeted compounds. Application of BL caused the mitigation of the Brz inhibitory effect and enhanced the BR level in duckweed treated with Brz. The level of BRs was reported for the first time in duckweed treated with BL and/or Brz.

Automated summary

Brassinolide and Brassinazole have concentration-dependent effects on the growth and biosynthesis of Wolffia arrhiza, with 0.1 mu M Brassinolide showing the most stimulatory effects on growth and levels of various compounds in the plant. Meanwhile, 1 mu M and 10 mu M Brassinazole caused significant decreases in duckweed weight and targeted compound levels. Moreover, Brassinolide mitigated the inhibitory effect of Brassinazole and enhanced the BR level in duckweed treated with Brassinazole for the first time.