PLANT RADIORESISTANCE AND DNA-REPAIR EFFICIENCY IN CHLAMYDOMONAS-REINHARDTII AND PISUM-SATIVUM

This paper compares the repair of DNA single strand breaks (ssb) induc ed by gamma-radiation in two strains of Chlamydomonas reinhardtii (137 C/+/ and UVS-I) and three lines of Pisum sativum (NN 131, 198, 140) di ffering in the degree of radioresistance. DNA ssb in cells exposed to gamma-rays (50, 100, 200, 500 Gy) were measured by electrophoresis and alkaline unwinding method with subsequent chromatography on hydroxyap atite immediately after irradiation and after 30 min of post-irradiati on incubation at 25-degrees-C. An increase of double-strand DNA (in %) was found in cells after 30 min post-irradiation incubation. C. reinh ardtii strains displayed an equal level of DNA degradation and repair efficiency in the DNA single strand breaks. The radioresistant line N 198 of P. sativum is characterized by a lower level of induced DNA ssb and higher efficiency of repair of these breaks as compared with less radioresistant lines NN 131 and 140.