Effects Of CO₂Enrichment And UV-B Enhancement On The Growth And Antioxidant System Of Nostoc Commune

With the soaring of global population and the rapid development of industry, the environment problems become more and more serious. Among them, the enrichment of CO2and the decomposing of ozone layer get most concern. And the change of these two environment factors will inevitably affect the algae which is the most important primary producer. In this article, we set the Nostoc commune as the experimental object, investigating the impact on the antioxidant system and the growth of Nostoc commune. Below shows the main results.1、After UV-B treatment, the content of photosynthetic pigments (such as: chlorophyll a, phycocyanin and allophycocyanin) of N. Commune is decreased significantly. But UV-B radiation has no negative effect on the dry weight of N. Commune, and increases the dry weight. However, high concentration CO2can reduce UV-B radiation injury, makes the pigment content maintain at a higher level, and improve the dry weight of N. Commune, further.2、After the enhancement of UV-B radiation, Nostoc commune increases the content of UV-screen pigments, such as MAAs and Scytonemin, to reduce or filter the UV-B radiation, stoping them from invading the cell. And the enriched CO2would increase the content of MAAs and Scytonemin further.3、Confront the stress which is brought by UV-B radiation, N. commune would make the antioxidant, for example PE and Car, remain relatively high level to protect the photosynthesis system and provide security for the efficient photosynthesis. And the enriched CO2could increase the content of PE, but it almost has no effect on the content of Car.4、To deal with the enhanced UV-B radiation, N. commune will enhance the activity of antioxidant enzymes(CAT and SOD) to eliminate the ROS created by the UV-B radiation and regulate the expression of genes to reduce the generation of ROS and to accelerate the eliminating of ROS. And the enriched CO2could increase the activity of antioxidant enzymes and regulate gene expression to reduce the ROS further.5、As a result of these metabolism changes, the adaption to UV-B radiation of N. commune is enhanced and the dry weight and growth rate of N. commune increase. However, the enrichment of CO2will reduce the negative effect of UV-B radiation and enhance the UV-B resistance of N. commune, promoting its growth further.