Anthocyanins and flavonols content in leaves of Rutaceae Juss family representatives as markers of stress tolerance

Abstract

Aims. To determine the seasonal dynamics and sex-related patterns of anthocyanins and flavonols accumulation in representatives woody plants of the Rutaceae Juss family (♂ + ♀ Ptelea trifoliata L., ♂ + ♀ Phellodendron amurense Rupr., Tetradium daniellii (Benn.) T.G. Hartley) under temperature and drought stress in the conditions of Kyiv. Methods. The quantitative content of anthocyanins was determined spectrophotometrically at 530 nm, and that of flavonols at 390 nm, recalculated as cyanidin-3-glucoside and rutin equivalents, respectively. Samples were collected during the summer (July 2024) and winter (February 2025) periods. Statistical analysis was performed using IBM SPSS Statistics 27.0.1, with a significance level of α = 0.05. Results. Distinct seasonal and sex-related differences in flavonoid content were observed. During the summer period, the highest anthocyanin content was recorded in ♂ P. trifoliata (137.14 mg/100 g), and the lowest in ♀ individuals (88.42 mg/100 g). In ♀ Ph. amurense, anthocyanin levels remained consistently high (124.44 mg/100 g), while in ♂ trees they were significantly lower. The highest flavonol content was detected in T. daniellii (41.30 mg/100 g DW), which is likely associated not only with its response to heat stress but also with increased metabolic activity during the flowering phase and the potential photoprotective function of these compounds. In the winter period, the maximum anthocyanin content was observed in ♀ P. trifoliata (97.02 mg/100 g), and the highest flavonol content in ♀ Ph. amurense (30.48 mg/100 g). Sexual dimorphism was evident across all species, indicating different levels of metabolic activity under stress conditions. Conclusions. Anthocyanins and flavonols serve as indicators of stress responses in woody Rutaceae species under temperate climatic conditions. A high anthocyanin content under extreme temperatures reflects stress intensity rather than enhanced tolerance. P. trifoliata exhibits the highest cold and heat tolerance, while T. daniellii shows the lowest. The obtained results have confirmed the feasibility of using flavonoid content as a diagnostic indicator of the physiological and biochemical adaptation of introduced Rutaceae species.