Tolerance Mechanism Of Paeonia Ostii To Cu, Relationship Between Paeonol And Antioxidation

Paeonia ostii could be used as nice seedstock for grafting ornamental peonies, for it has strong roots and good stress resistance, while its dried root bark ("Cortex Moutan") is also one of the chinese medicinal materials. In Fenghuang Mountain area of Tongling in Anhui province, where Cu content of soil is high, P. ostii is widely planting and growing well. It demonstrates the potential of P. ostii for phytoremediation on the the Cu tailings. In view of P. ostii’s strong tolerance to Cu, the following were the study of Cu resistance mechanism of P. ostii by two aspects.1. By culturing with2-year-old seedlings of P. ostii and treating with different level of added Cu treatments, with pot experiment in Heze, Shandong province, the following was studied to clarify physiological mechanism of Cu resistance in P. ostii:physiological responses and resistance to Cu oxidative stress, distribution and absorption of mineral ions in P. ostii.2. By the same pot experiment in three different growing areas (Tongling, Anhui province; Heze, Shandong province; Shaodong, Hunan province), the study used2-year-old seedlings of P. ostii as material and treated with different Cu treatments as above. The contribution of paeonol to Cu resistance was explored, by comparing the appearance characters and bioactive components of Cortex Moutan among these three areas, and analyzing the relationship between the paeonol content and antioxidation of P. ostii. The study further revealed the P. ostii mechanism of Cu resistance, and that could provide a theoretical basis for P. ostii remediation of Cu contaminated soils.1. Effects of Cu on growth, physiology, and element absorption and distribution in P. ostiiA pot experiment was conducted to study the tolerance of P. ostii to different levels (low,300mg·kg-1; medium,600mg·kg-1; and high,900mg·kg-1) of added Cu. P. ostii had strong tolerance to Cu. The plant height and root collar growth, taproot thickening and elongation, and biomass of roots and shoots were less affected. Under the Cu treatments, the tolerance index of roots and shoots was higher than0.5. Superoxide dismutase (SOD) activity in roots decreased significantly under the Cu treatments, but that in leaves increased significantly under low Cu treatment. Peroxidase (POD) activity in roots and leaves and decreased after an initial increase. The MDA both in roots and in leaves did not have a significant increase under low and medium Cu treatments. The soluble sugar and soluble protein contents in roots and leaves increased with increasing concentration of added Cu, while the contents of chlorophyll a, b, and a+b and the chlorophyll a/b ratio were peaked at medium Cu treatment. With increasing concentration of added Cu, the Cu content in roots and stems increased, while that in leaves decreased after an initial increase. The Cu enrichment coefficient in each part of the plant under the Cu treatments was less than1.0. The Cu treatments led to a significant reduction in the P and Ca absorption, but promoted the upward translocation of absorbed P and K. Low and medium Cu treatments promoted the Mg accumulation in leaves, but high Cu treatment inhibited it. The Fe and Mn accumulation in roots was inhibited under the Cu treatments, while the Fe and B accumulation in leaves and the upward translocation of absorbed Fe, Mn, Zn, and B were promoted under low and medium Cu treatments. The accumulation of Zn in each part of P. ostii was less affected by the Cu treatments.2. Effect of Cu on quality of Cortex Moutan and correlation between the quality and antioxidationBy planting P. ostii in different ecological zones with the same Cu treatements, we compared and analyzed the effect of Cu on the conventional quality of Cortex Moutan, and correlation between the synthesis of paeonol under Cu treaments and resistance to oxidative stress in P. ostii. The results showed that:The root dry weight, root length and coarseness, xylem and phloem coarseness, and phloem/xylem were less affected by the low Cu treatment. Polysaccharide content in roots of Shandong increased significantly under low Cu treatment, but that in the other two places was less affected. Under the medium Cu treatment, the appearance characters in Shandong and Anhui were less affected, but that in Hunan decreased significantly with exception of duramen coarseness, paeonol content in Anhui increased significantly, but that in Shandong was less affected and decreased significantly in Hunan, polysaccharide content in Shandong was less affected, but that in the other two places decreased. Under the high Cu treatment, the appearance characters and paeonol contents in roots of the three places decreased significantly, polysaccharide in Shandong was less affected, but that in the other two were significantly inhibited. Correlation analysis between the paeonol content and antioxidation of P. ostii showed that peroxidase (POD) activity In P. ostii roots of three places was positively related with paeonol content, while MDA content showed a nagative correlation with paeonol content.