Laser Enhanced Uv-b Radiation Vicia Faba Seedlings Injury Protection And Repair,

An increase of the concentration of MDA and rate of electrolyte leakage of cellular membrane in broad bean (Vicia faba L.) plant was induced by exposure to enhanced UV-B irradiation. Moreover, UV-B irradiation caused DNA damage to yield CPD (dimer) between two adjacent thymines in plant DNA. As a result, the plants were damaged by increased UV-B radiation. However, laser was found to be capable to protect and repair plants from UV- B-induced damage. In research for laser role of protecting plants from UV-B irradiation, it was shown that primary response to UV-B radiation damage in plant was to increase the UV absorbing compounds. Laser irradiation increased the UV absorbing compounds in order to protect plants from UV-B radiation. Thus, an increase of content of UV absorbing compound by laser irradiation was strengthened primary response to UV-B radiation damage. The secondary responses to UV-B radiation in plant were participated in ASA, GSH and antioxidative enzymes SOD, CAT and APX. If UV-B treatment on plants following laser radiation, laser irradiation could build-up the content of ASA and GSH, and increase the activities of SOD, CAT and APX to protect plants from enhanced UV-B radiation. Meanwhile, laser irradiation improved the content of soluble protein and stimulated expression of some genes of 搕hreatening proteins? which was called "the third responses to increased UV-B radiation in plant employing laser treatment on UV-B-induced damage"in this paper. These proteins could help plants to strengthen protecting from UV-B irradiation. Laser repair role on UV-B-induced plant damage mainly appeared plant DNA repair role. On the one hand, laser irradiation was capable to increase the activity of photolyase and thus shortened the recovery time of DNA damage. On the other hand, this paper employed T4EndoV as a symbol to test the quantitation of CPD. The results were shown that increased UV-B radiation caused plant DNA damage and yielded a lot of CPD5. However, if using laser treatment on UV-B-induced plant damage, we found that the quantitation of CPDs quickly decreased the normal level (without UV-B irradiation plant). Meanwhile, red light radiation had no effect on decreasing CPDs level. Thus, laser had obviously repair effect on UV-B-induced-damage in plant DNA strains. In further research for laser repair mechanism, it was found that laser repair was a new pathway-laser repair of breaking bonds. Laser irradiation could break CC bonds in CPD and thus made CPD monomer. As a result, plant DNA damage was repair and plant DNA transcription and expression became normal. Laser protection of plant from UV-B radiation damage was obvious and would be employed in agriculture in future. Furthermore, this paper was found a new plant repair pathway-laser repair of breaking bonds in CPD, whichwould pioneer a new field of researching for DNA damage and repair.