Responses of photosynthetic properties and chloroplast ultrastructure of Bryum argenteum from a desert biological soil crust to elevated ultraviolet-B radiation.
Our understanding of plant responses to enhanced ultraviolet-B (UV-B) radiation has improved over recent decades. However, research on cryptogams is scarce and it remains controversial whether UV-B radiation causes changes in physiology related to photosynthesis. To investigate the effects of supplementary UV-B radiation on photosynthesis and chloroplast ultrastructure in Bryum argenteum Hedw., specimens were cultured for 10 days under four UV-B treatments (2.75, 3.08, 3.25 and 3.41 W m(-2) ), simulating depletion of 0% (control), 6%, 9% and 12% of stratospheric ozone at the latitude of Shapotou, a temperate desert area of northwest China. Analyses showed malondialdehyde content significantly increased, whereas chlorophyll (Chl) fluorescence parameters and Chl contents decreased with increased UV-B intensity. These results corresponded with changes in thylakoid protein complexes and chloroplast ultrastructure. Overall, enhanced UV-B radiation leads to significant decreases in photosynthetic function and serious destruction of the chloroplast ultrastructure of B. argenteum. The degree of negative influences increased with the intensity of UV-B radiation. These results may not only provide a potential mechanism for supplemental UV-B effects on photosynthesis of moss crust, but also establish a theoretical basis for further studies of adaptation and response mechanisms of desert ecosystems under future ozone depletion.
Shapotou Desert Research and Experiment Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, P. R. China.
Rong
R
Hui
Xinrong
X
Li
Cuiyun
C
Chen
Xin
X
Zhao
Rongliang
R
Jia
Lichao
L
Liu
Yongping
Y
Wei
D019068:Bryopsida / Q000502:physiology* / Q000528:radiation effects*; D002338:Carotenoids / Q000378:metabolism; D002681:China; D002734:Chlorophyll / Q000378:metabolism / Q000528:radiation effects; D002736:Chloroplasts / Q000528:radiation effects / Q000648:ultrastructure*; D003889:Desert Climate; D017753:Ecosystem; D005453:Fluorescence; D015227:Lipid Peroxidation / Q000528:radiation effects; D008315:Malondialdehyde / Q000378:metabolism; D010788:Photosynthesis / Q000528:radiation effects*; D010940:Plant Proteins / Q000378:metabolism; D020524:Thylakoids / Q000378:metabolism / Q000528:radiation effects; D014466:Ultraviolet Rays
D010940:Plant Proteins; D002734:Chlorophyll; D002338:Carotenoids; D008315:Malondialdehyde