RESPONSES TO CONTINUOUS AND DISCONTINUOUS NACL STRESS OF LONG-TERM CULTURED RICE (ORYZA-SATIVA L) CELLS

Rice (Oryza sativa L.) cells, grown under a continuous stress of 1.5% NaCl, produced a homogeneous mass of dry, compact, nodular callus with high regeneration potential, typical of embryogenic cultures. When tr ansferred and subcultured in conditions without salt, the pre-adapted cells underwent several changes, leading to the formation of heterogen eous populations that comprised different cell types. This newly forme d callus, in the 6-month period without salt stress, resembled cell po pulations of the untreated cultures. These cells are characterized by fast growth, high water content, friable texture, high salt sensitivit y and low culture response. They also produce a protein pattern in the SOS-PAGE analysis, that differs from that of cells cultured under the continuous salt stress. This observation indicates that different sal t stress regimes induced different responses in the cultured cells in rice.