EFFECTS OF WATER-STRESS ON PLANT-GROWTH AND ROOT PROTEINS IN 3 CULTIVARS OF RICE (ORYZA-SATIVA) WITH DIFFERENT LEVELS OF DROUGHT TOLERANCE

Rice (Oryza sativa L.) is considered a drought-sensitive crop species; however, within this species, there are considerable varietal differe nces in sensitivity to this environmental stress. in the present work, the effect of water stress on germination, plant growth and root prot eins in three rice cultivars (Sinaloa, IR10120 and Chiapas) was analyz ed. Seed germination and plant growth were found to be significantly i nhibited by polyethylene glycol (PEG)-imposed water deficit in cv. Sin aloa; cvs IR10120 and Chiapas were more tolerant to water stress. Fluo rographs of two-dimensional electropherograms of in vivo-labeled polyp eptides were analyzed to identify changes in the root protein patterns that resulted when plants were grown in the presence of 10% PEG for 1 0 days. The treatment induced or increased the synthesis of eight poly peptides or groups of polypeptides in cv. Sinaloa, seven in cv. IR1012 0 and four in cv. Chiapas. The synthesis of several polypeptides was d ecreased by the PEG treatment in cv. Sinaloa and cv. IR10120. Most of these PEG-induced changes in the root protein patterns were cultivar-s pecific and only one 26-kDa protein with a pi of 6.0 was induced by wa ter deficit in the two cultivars Sinaloa and IR10120.