The Physiological Responses Of Catharanthus Roseus Seedling To Copper Stress And The Involved Role Of Ethylene During This Process

In the present study, to investigate responses of Catharanthus roseus to copper stress and roles of ethylene during this process, Catharanthus roseus was conducted to different concentrations of copper in combined with exogenous ethylene or not. Primary metabolism, accumulation and transferation of Cu as well as antioxidant system were analyzed. Besides, the ability of Catharanthus roseus being a Cu accumulator was also tested.The results of the study are as follows:1. Low concentration of Cu promoted growth of Catharanthus roseus, chlorophyll content and photosynthetic rate were increased after Cu treatment. Also, root system of Catharanthus roseus displayed increased tolerance to Cu. on the other hand, application of exogenous, precursor of ethylene biosynthesis, did not decrease damage to Catharanthus roseus induced by Cu, above ground biomass, chlorophyll content as well as photosynthesis rate were decreased. Although obvious damage was detected in root system, its increased tolerance and adaptive ability to Cu were also observed.2. Under Cu conditions, Catharanthus roseus accumulated large amounts of Cuand Cu in the body transferred from mature tissues to young tissue; when exogenous ethylene were applied to copper stressed Catharanthus roseus, roots ability that accumulate Cu was inhibited significantly, transportation of Cu across tissues were also suppressed, indicating that exogenous ethylene alleviated Cu induced damage to Catharanthus roseus efficiently.3. Under the condition of copper stress, stimulus accumulation of H2O2in the cell will be poison to macromolecules in cell. MDA, soluble sugar content increased, to a certain extent weakened the toxic effect caused by heavy metals to plants. One of the important mechanisms of Cu is harmful to plants is that ROS caused by Cu, and plant through the SOD, CAT and POD to eliminate or reduce the harm that ROS. Adding exogenous ethylene to copper stress, reduced Cu induced damage to plant.4. The plant alkaloid content change characteristics conform to the general law of the change of the alkaloids:content is higher in young group, as the organization gradually mature, content gradually reduced, with maximum efficiency to keep the normal plant development and growth. Analysis of alkaloid content in different leaf blade concluded:blade spirit and alkali content is higher, and the upper part of the two highest alkaloid content in young leaves. And exogenous copper and ethylene processing seedlings can promote indole alkaloids content increase, but also improves four key enzyme genes in biosynthesis pathway, to better promote the synthesis of many spirit, and promote more spirit and vinb synthetic vinblastine, thus raising the indole alkaloids content, including vinb content to improve the most significant.