Chemical Nature of Radiation-Induced Single-Strand Breaks in the DNA of Dormant Barley Seeds in Vivo

Abstract

Gamma irradiation of dormant barley seeds has led to the production of DNA single strand breaks, the liberation of inorganic phosphate, and the formation of phospho monoester groups. For each single-strnad break produced in DNA, 0.22 molecules of inorganic phosphate were liberated and 1.1 molecules of phosphomonoester groups were formed. Of the phosphomonoester groups formed, 40% were 5'-phosphomonoesters. Only 8.6% of the 5'-termini produced by radiation were 5'-hydroxyl termini. The chemical mechanisms involved in the induction of single-strand breaks in the DNA of dormant barley seeds are discussed.