Occurrence of brassinosteroids and influence of 24-epibrassinolide with brassinazole on their content in the leaves and roots of Hordeum vulgare L. cv. Golden Promise

Abstract

Main conclusion 24-epibrassinolide overcame the inhibitory effect of brassinazole on the barley growth and the content of brassinosteroids. The present work demonstrates the occurrence of mainly castasterone, brassinolide and cathasterone and lower amounts of 24-epibrassinolide, 24-epicastasterone, 28-homobrassinolide, typhasterol, 6-deoxocastasterone and 6-deoxotyphasterol in 14-day-old de-etiolated barley (Hordeum vulgare L. cv. Golden Promise). We also investigated the endogenous level of brassinosteroids (BRs) in barley seedlings treated with 24-epibrassinolide (EBL) and/or brassinazole (Brz). To our knowledge, this is the first report related to the occurrence of BRs and application of EBL and Brz in terms of the endogenous content of BRs in barley. Brz as a specific inhibitor of BR biosynthetic reactions decreased the level of BRs in the leaves. Application of EBL showed a weak promotive effect on the BR content in Brz-treated seedlings. Brz also inhibited growth of the seedlings; however, addition of EBL overcame the inhibition. The EBL applied alone at 0.01-1 µM increased the BR level in the leaves but at 10 µM lowered the BR content. In opposition to leaves, the Brz in the concentration range from 0.1 to 1 µM did not significantly affect the content of BRs in the roots. However, application of 10 µM Brz caused BRs to decrease, but treatment of EBL concentrations overcame the inhibitory effect of Brz.

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

“…These results are similar to the studies of Janeczko and Swaczynova [ 49 ], who demonstrated the increases of endogenous content of BL and CS in wheat ( Triticum aestivum ) seedlings treated with 0.1 µM EBL. The stimulatory effect of 0.1 µM EBL on the level of BRs in barley ( Hordeum vulgare ) was also reported [ 48 ].…”

“…Similarly to the growth rate, the most increase of BRs’ level was reported under the influence of 0.1 µM BL, while during the treatment with 1 µM BL, the content of BRs declined. These BRs’ level alterations may be associated with the direct effect of exogenously applied BRs on their biosynthetic pathways [ 48 ]. Furthermore, the application of BL to hydroponically cultured duckweed influenced the considerable absorption of BL manifested in the increases of its endogenous level.…”

“…Besides growth reduction, Brz- treated cress exhibited curled, dark-green leaves [ 21 ]. The inhibitory effect of Brz on the hypocotyl elongation in seedlings of barley [ 48 ], cucumber, tomato ( Solanum lycopersicum ), and tobacco ( Nicotiana tabacum ) [ 20 ], or A. thaliana [ 19 ] was also reported. Thus, the phenotype modifications of Brz-treated plants are similar to the genetically modified BR-deficient mutants.…”

“…Concerning the literature data, exogenous BRs’ influence on their accumulation in plants treated with Brz was exceptionally rarely studied. It was reported that exogenous EBL application overcame the inhibition of BRs’ synthesis caused by treatment with Brz [ 48 ]. Thus, the previous research on W. arrhiza showed the reduction of fresh weight, proteins, and monosaccharides’ content in cultures treated with Brz2001 and their restoration after application of EBL [ 31 ].…”

Comprehensive Overview of the Brassinosteroid Biosynthesis Pathways: Substrates, Products, Inhibitors, and Connections

“…Brz decreased the level of BRs in the barley leaves, but not in roots. The inhibition effect of Brz on plant growth is reversed by exogenous BR ( Bajguz and Asami, 2004 ; Bajguz and Asami, 2005 ; Bajguz et al., 2019 ).…”