Content and balance of endogenous brassinosteroids in potato microclones is determined by the organ specificity and term of ripening variety

The endogenous brassinosteroids content in the roots and shoots of early- and mid-season potato microclones was determined. Among the analyzed plant steroid hormones were representatives of brassinolide group, 24-epi- brassinolide group, 28-homobrassinolide group, B-lactones and B-ketons. The level of all brassinosteroids in plant roots exceeded significantly that in shoots, irrespective of the potato term of ripening. Of interest is the fact that in plant shoots there were no BS groups of 24-epibrassinolide. We have first found a relationship between the terms of potato ripening and endogenous content of different BS groups in the aerial and underground plant parts; we have also assessed the age-related changes in the content of BSs, as well as their ratio in the potato plants of the Red Scarlett variety.