Seasonal Changes In The Contents Of Pigments And Antioxidative System Of Sabina Przewalskii And Sabina Chinensis

Suitable environment temperature plays a vital role in plant normal growth, and when environment temperature drops to certain degree, the plant will be injured and even die. Research the mechanism of chilling stress on plant and explore preventive measures have important theoretical and practical significance. In chilling stress the plant must cause corresponding adaptation or quick defense reactions which can avoid cold happen. However, there was few report about the physiological mechanism of evergreen plants of Sabina in northwest China during chilling stress. The leaves of Sabina przewalskii and Sabina chinensis were used to explore the cold resistant mechanism by examining seasonal changes of the pigment system and antioxidant system. To clarify chilling stress mechanism.of evergreen woody plants Sabina przewalskii and Sabina chinensis, the relationship between the pigments system and antioxidative system and the environment were discussed in this study. The main results were obtained as follows:1. The seasonal changes of pigments syetemThe contents of anthocyanins were correlated with temperature variations. When the temperature is lower, anthocyanins sharply increased and in winter anthocyanins was far above than other seasons. The seasonal changes of anthocyanins synthase PAL and UFGT the same as anthocyanins,and PAL and UFGT activity were very significant positive correlation with anthocyanins contents, they are the key enzyme in anthocyanins synthesis. indicating that anthocyanins might act as a signal molecule when these species were exposed to low temperature conditions. Anthocyanins synthesis need sugar source, in the two specials the contents of soluble sugar, sucrose and fructose contents in anthocyanins accumulation phase also sharply increased, and are very significant positive correlation with anthocyanins contents.while starch in winter lower than other seasons. The activity of invertase AI and NI were negatively correlated with sucrose changes, the SPS was significantly positive correlation.The contents of flavonoids in winter was higher than other seasons in the two specials, explained that flavonoids can resist the low-temperature. The rhodoxanthins also varies with temperature drop rises, the (A+Z)/(V+A+Z) and carotenoids rised when temperature decreases, while the seasonal changes of chlorophylls showed an opposite pattern. These results supported that seasonal changes of the pigments were associated with temperature and light acclimation in the two species.2. The seasonal changes of antioxidative system:The components of ASA-GSH cycle in two species were higher in winter than other seasons. The results suggested that the ASA-GSH cycle were related with antifreeze and antioxidant.The activity of GR, DHAR,APX and the contents of ASA,GSH, Pro in Sabina przewalskii all were higer than in Sabina chinensis, but the contents of MDA in Sabina chinensis was higer, so the lipid peroxidation in Sabina chinensis also was higer, in that case plant usually need more ASA to clear free radicals. At the same time, the higer activity of DHAR and APX were necessary to generate a lot of ASA, therefore, the ASA-GSH cycle enhanced antioxidant was an adaptation to the adverse environmental of low temperature. Sabina przewalskii had stronger abilities for stress resistance than Sabina chinensis, which was related with Sabina przewalskii had better adaptability to their environment along the strong light and altitude gradient.The anthocyanins contents were significantly positive correlation with Rho,VAZ,APX,GR,ASA,GSH in Sabina przewalski, Rho and VAZ can act for low temperature and light protection. ASA, GSH, APX and GR were increased due to resistance to oxidative stress caused by low temperature, This indicated that anthocyanin was associated with oxidation resistance under low temperature conditions. There were coregulate between anthocyanins, pigments and ASA-GSH cycle. Consequently, a network of antifreezing, antioxidation and photoprotection were formed in Sabina.przewalskii. We found that there were positively correlated or no significant correlations were occurred between anthocyanins and other pigments and AsA-GSH cycle in Sabina chinensis. This indicated that the antioxidative ability in Sabina przewalskii is stronger than Sabina chinensis.