Laser pretreatment protects cells of broad bean from UV-B radiation damage

In order to determine the role of lasers in the stress resistance of broad bean (Vicia faba L.) to ultraviolet-B (UV-B) radiation, the embryos in seed s were exposed to He-Ne laser or CO2 laser radiation. Afterwards they were cultivated in Petri dishes in a constant temperature incubator until the le ngths of epicotyls were nearly 3 cm. The epicotyls were then exposed to 1.0 2, 3.03 or 4.52 kJ m(-2) UV-B radiation, respectively, under 70 mu mol m(-2 ) s(-1) photosynthetically active radiation (PAR) in a growth cabinet. Chan ges in the concentration of malondialdehyde (MDA), ascorbic acid (AsA) and UV-B absorbing compounds (absorbance at 300 nm) were measured to test the e ffects of laser pretreatment. The results showed that laser pretreatment of embryos enhanced W-B stress resistance in the epicotyls of the broad bean by decreasing the MDA concentration and increasing the content of AsA and U V-B absorbing compounds. We suggest that those changes in MDA, AsA and UV-B absorbing compounds were responsible for the increase in stress resistance observed in the broad bean. This is the first investigation reporting the use of laser pretreatment to protect the cells of the broad bean from UV-B- induced damage. (C) 2000 Elsevier Science B.V. All rights reserved.