SALT STRESS-INDUCED NUCLEAR AND DNA-DEGRADATION IN MERISTEMATIC CELLSOF BARLEY ROOTS

Root growth of barley (Hordeum vulgare L., cv. Akashinriki) was inhibi ted by 200 mM NaCl, when 1 mM CaCl2 was present in the hydroponic cult ure solution. Increasing the CaCl2 up to 10 mM partially prevented thi s inhibition. However, inhibition also occurred with 100 mM NaCl in th e presence of 0.1 mM CaCl2. The nuclei of meristematic cells in roots in which growth had been inhibited by salt stress were studied after s taining with DAPI (4',6-diamino-2-phenylindol). Nuclear deformation of the cells occurred with 12 h of salt stress with 500 mM NaCl, and was followed by degradation. The nuclear degradation was also observed wh en the roots were exposed to more than 300 mM NaCl for 24 h. Biochemic al analysis revealed that nuclear degradation was accompanied by apopt osis-like DNA fragmentation, The intracellular mechanisms of nuclear d egradation in cells after salt stress are discussed.