Seasonal changes in anthocyanin contents and in activities of xanthophyll and ascorbate–glutathione cycles in Sabina species derived from different environments

Qilian Juniper (Sabina przewalskii Kom.) and Chinese juniper [Sabina chinensis (Lin.) Ant.] are overwintering plants. S. przewalskii, a protected species in China, is distributed in subalpine and alpine area on the Qinghai-Tibet Plateau. S. chinensis is distributed in plain area. We investigated seasonal changes in photoprotective stress compounds such as anthocyanins, activities of three enzymes of ascorbate–glutathione pathway, as well as xanthophyll size and conversion in these species. Ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) levels were higher in the lowtemperature months, which was associated with changes in anthocyanins and in de-epoxidation index [(A + Z)/ (V + A + Z)]. Photochemical efficiency of PSII (Fv/Fm) was lower (<0.70) during winter and late autumn in both species. During the low-temperature months, S. przewalskii had higher levels of photoprotective stress compounds than S. chinensis. The results suggested that these two species possess cold-induced photoinhibition functions and show the inherent, season-dependent differences in the amounts of the stress-related compounds.