摘要
研究了UV-B增强及可见光修复对真藓生理特性和细胞超微结构的影响。结果表明,增强UV-B会使真藓的光合色素、类黄酮含量及抗氧化酶活性下降,丙二醛(MDA)含量升高,细胞超微结构遭到破坏,表现为叶绿体结构变形,类囊体片层排列稀疏紊乱、膨胀甚至模糊不清,嗜锇颗粒增多,并且UV-B辐射强度越大,损伤越大;而可见光可以部分修复增强UV-B对真藓生理特性及细胞超微结构引起的损伤。研究探索了真藓对UV-B辐射的响应及自身修复能力,对于进一步理解真藓对UV-B辐射的耐受机理具有重要的理论意义。
Over the last several decades,significant reductions in the concentrations of stratospheric ozone（O3） have been reported.The reduced ozone concentration causes an increase in the UV-B radiation that reaches the earth’s surface;this is one of the most important environment problems worldwide.Although UV-B radiation accounts for only about 1.5% of total solar radiation,it is readily absorbed by biomacromolecules,with the result that increased UV-B radiation inhibits the growth of most plants.Biological soil crusts（BSCs） are complex assemblages of minute organisms that are formed primarily by cyanobacteria,green algae,lichens,and mosses on the surface of soil.Previous studies have shown that increased UV-B radiation has detrimental effects on BSCs.However,we observed that they can recover from UV-B stress,and still flourish in desert regions.Moss crust has great ecological significance in desert areas,where it is the dominant component of BSCs,and a major pioneer species in community succession processes.In desert ecosystems,plant life is damaged as a result of adverse environmental conditions,such as strong light,extreme temperature,salinity,and water deficit.Several studies have examined the effects of environmental factors on the species composition and physiological properties of BSCs.However,fewer studies have addressed the recovery mechanisms of BSCs after they are subjected to environmental stresses.We used UV-B radiation（2.75,3.08,3.25 and 3.41 W/m2） to simulate the depletion of 0%（control）,6%,9% and12% of stratospheric ozone at the latitude of Shapotou region and recovery after a return to visible-light conditions（150μmol m-2s-1） and evaluated the effects of this exposure on physiological variables and cell ultrastructure in the moss Bryum argenteum,which we isolated from BSCs in the Tengger Desert in northern China.The results indicated that the photosynthetic pigments content,flavonoid content,and antioxidant enzyme activity in B.argenteum decreased,while malondialdehyde（MDA） content increased after exposure to UV-B radiation.The ultrastructure of the chloroplasts of B.argenteum subjected to enhanced UV-B was significantly disrupted,as follows：the chloroplast structure was distorted,the arrangement of the thylakoids in the chloroplast was disordered,expanded or even obscured,and the number of osmiophilic granules increased.The degree of damage increased with increasing UV-B radiation.However,visible light could partially repair damage induced by enhanced UV-B radiation.The aim of the present study was to discuss the responses of B.argenteum to UV-B radiation and its repair capabilities,and to improve the understanding of the mechanisms of the tolerance of B.argenteum to UV-B radiation.
出处
《生态学报》
CAS
CSCD
北大核心
2016年第11期3450-3458,共9页
Acta Ecologica Sinica
基金
国家自然科学基金项目(41271061
41371100)
中国科学院西部之光博士项目
关键词
UV-B
真藓
光合色素
叶绿体超微结构
光修复
UV-B
Bryum argenteum
photosynthetic pigments
chloroplast ultrastructure
light recovery
