| Enhancement of UV-B radiation caused by decrease of the atmospheric ozone layer directly or indirectly leads to change of plant in morphology, photosynthesis and genetic structure. Therefore, it has become a hot topic that researches in various ways and different levels on the mechanism of plant responses to UV-B radiation may make a theoretical and practical significance. In this study, Glycyrrhiza uralensis Fisch which habitat in arid and semi-arid area was used,by means of anatomy, to explore the morphological and ultrastructural difference and Ca+distributional change of the leaf that harvest in different growth conditions such as field in different regions and artificial chamber. The results show that:The Glycyrrhiza uralensis Fisch. grown in three different habitats, their leaves were bright green and structure is complete. While in epidermal cells and the arrangement of mesophyll palisade tissue cell, inclusions, palisade tissue cell ultrastructure and cutical layer structure, are obviously different. It is caused of not only the environment temperature and relative humidity, the light conditions, especially the existing in the spectrum of UV B radiation may also be one of the influencing factors.Indoor simulation the three different habitats of UV-B radiation intensity, with10000lx fluorescent lamp for PAR, increase UV-B radiation treatment, observing the UV-B radiation effects on leaf morphology and structure. Results show that after different UV-B radiation, the morphology and structure of the leaves were showed different degrees of damage. On the morphology, with the increase of UV-B radiation dose or irradiation time prolonged, the leaf, in turn, appear curly, water loss, local brown spots, large area of Browning, death, fall off wait for a phenomenon. Further observation, we found that UV-B radiation can change the structure of blade organization and the mesophyll cell, the degree of change is a close relationship with the radiation dose and time. After low doses (4μW/cm2) of UV-B treat2-4days, leaf microstructure has no difference between control and radiation treatment. But after6days radiation, cutin membrane thickness increase compared with controls, the inner cutical layer mesh structure is more and more obvious, wax is dyeing deeper. But as the radiation time continue to extend, also gradually, the phenomenon of the structure destroyed by part. On the contrary, after middle and high dose of UV-B (14μW/cm224μW/cm2) treating for2days, the palisade tissue cells and epidermal cells are obvious deformation, and with the times’going, the epidermal cells were dead, Chloroplasts of palisade tissue cells, organelles such as mitochondria structure damage, or even collapse, organelles structure changes are similar to cell apoptosis phenomenon.We have looked at the Ca2+distribute in the leaves of Glycyrrhiza uralensis Fisch. grow up in three different environment and artificial simulation under the condition of UV-B radiation. It vary in different habitats, indoor least calciumions. After different doses UV-B radiation treatment, there are significant differences in ca2+distribution and it moved from outside the cell wall to beside the cell vacuole, then moved to the chloroplast gathered around, change to cell membrane gathered phenomenon, in the end. Visible, Ca2+participated in the UV-B radiation signal transduction in the series process during the Glycyrrhiza uralensis Fisch. leaf palisade tissue cells, and even participate in the induction of palisade tissue signal transduction process of programmed cell death. |
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