Proline controls the level of polyamines in common sage plants under normal conditions and at UV-B irradiation | Пролин регулирует уровень полиаминов в растениях шалфея в нормальных условиях и при УФ-В облучении

Salvia officinalis L. plants were grown in a water culture to the stage of 4–5 true leaves. The they were treated by proline (PN) added to the nutrient medium to a final concentration of 5 milli mole or by ultraviolet-B light (12 300 joule/square meter for 10 minutes) or were subjected to combined action of these factors for 12, 24, 36, or 48 hours. Activity of proline dehydrogenase (PDH), a content of PN and contents of free and conjugated polyamines were determined in the leaves and roots. It was shown that a content of endogenous PN was close to zero in the control untreated plants and it was 9 micro mole/gram in the roots after 12 h of exposure, whereas in the leaves the content increased only after 24 h and achieved 1 micro mole/g. A content of free putrescine increased in the leaves and especially in the roots after 10-min irradiation with Uv-B light. A biosynthesis of putrescine was induced in presence of PN in medium and was observed earlier than after Uv-B irradiation. Uv-B irradiation also induced accumulation of their soluble conjugates. Exogenous PN enhanced putrescine synthesis but inhibited the formation of polyamine soluble conjugates. At combined treatment of the 2 factors, the content of free putrescine in the leaves displayed a tendency to the rise and in the roots, to the decrease. At the same time, the content of polyamine free conjugates increased in both leaves and roots. All these facts could be considered as an indirect indication of relationship between PN and polyamine biosyntheses. An artificially created high PN concentration characterized of its low constitutive level resulted in disturbances in a homeostasis of low-molecular cell metabolites and induced a requirement in its restoration by diverse ways. Induction of polyamine biosynthesis and changes in a content of their soluble conjugates might be one of the ways for such restoration. A high PN concentration is not toxic for plants under stress conditions, because polyamines and PN are components of a plant defense system, thus weakening damage effects of abiotic stressors.