The effect of exogenous 24-epibrassinolide on the ecdysteroid content in the leaves of Spinacia oleracea L.

• Exogenous 24-epibrassinolide causes changes of the ecdysteroid content in spinach plants.
• The content of five ecdysteroids was followed.
• The hormone application was performed at two concentrations.
• The response to treatment differed in younger and older leaves.

The aim of this study was to show whether/how the application of exogenous 24-epibrassinolide can affect the content of ecdysteroids in spinach leaves. Brassinosteroids and ecdysteroids, structurally related phytosterols, show effect on a range of processes in plants. Brassinosteroids increase biomass yield in some species, photosynthesis and resistance to stress, and ecdysteroids show effect on proteins responsible for binding of CO2 or water cleavage. The mutual interaction of these sterols in plants is unclear. The UPLC–(+)ESI-MS/MS analyses of extracts of treated and untreated spinach (Spinacia oleracea L.) leaves show that the application of exogenous 24-epibrassinolide does influence the ecdysteroid content in plant tissues. The response differs for the major ecdysteroids and also differs from that for the minor ones and is dependent on the developmental stage of the leaves within the same plant or the 24-epibrassinolide concentration applied.