Responses Of Sedum Aizoon L. To Added UV-B Radiation

Solar light is a foremost environmental factor of importance to plants, thephotoautotrophic organisms and primary producer. Owing to the stratospheric ozone layerdepletion which has been greatly affected by the emission of halogenated chemicals, theglobal solar ultraviolet irradiation, especially UV-B radiation reaching the earth’s surface isincreasing. But in the Antarctic, unprecedented ozone hole was still reported in2011byscientists from nine countries. However, there is few research data that how to judge thesensitive and nocuity of plants to UV-B radiation.Sedum aizoon L. is succulent plant, which have some predominant characters, such asdrought and salt sresistance, cuttage propagation, suitable to environment. Here weinvestigated the response of Sedum aizoon L. in natural condition, as well as the effect ofUV-B radiation on the changes of microstructure and physiological impact in leaves of Sedumaizoon L., using the plant anatomy and phytochemistry. In order to explore the feasibility thattreat Sedum aizoon L. as model species for detection of UV-B radiation. The results showedthat:1. Under light microscope, the stomas, which contain chloroplast, were arranged in upperepidermis in nature condition. The epidermal cells were presented satiation and not depositedany pigments or dead cell. Under fluroscence microscope, the cuticles with the character ofgiving off fluorescence were presented thin cover upon epidermal cell. The chloroplasts werebigger in mesophyll cells and scattered in a single around vacuole. Under added UV-Bradiation, the brown porphyritic pigments, which have covered the stomas, were located inepidermal cells. The overall epidermal cells were presented wilting shape, ever someepidermis cells collapsed. The cuticles were not obviously thickness after exposed UV-Bradiation. The chloroplasts were gathered together in mesophyll cells.2. Under natural condition, the water storeage capacity of leaves Sedum aizoon L. wasstrong. The leaves, which from budding to shedding, had a life span of2-3mouths. Afterexposed UV-B radiation, leaf aging of Sedum aizoon L. is accompanied by the formation ofan abscission. The complicated anatomical changes that during formation of the abscissionlayer were an enormous developmental achievement which includes cell division as well as cell differentiation. Then, the leaves were easily shedding from abscission layer at the affectedby outside force3. Under the condition of artificially added UV-B radiation, fresh weight, rate of DW/FW,the content of flavonoids, photosynthetic pigments and soluble protein were decreasedobviously than CK control, especially in juvenile of the fresh weight and photosyntheticpigments. The loss of water in leaves lead to decline of Photosynthesis rate and capacity.The activity of SOD, POD decreased significantly compared with the control in the leaves ofSedum aizoon L.. While, the rate of superoxide anion generation were obviously high inleaves under added UV-B radiation. The balance of generation and elimination of ROS werebroke and then the ROS were exceeded the capacity of elimination of Sedum aizoon L..All kinds of morphological structure and physiological prove that Sedum aizoon L.have a strongly sensitive and poorly capacity of repair to added UV-B radiation. Firstly,Sedum aizoon L. can act as model species to study the response to UV-B radiation. Secondly,we can treat Sedum aizoon L. as detecting plant for detection of UV-B radiation from ambientsolar,according to morphological structure. Therefore, we conclude that it is feasibility thatconsider Sedum aizoon L. as model species for detection of UV-B radiation.