Abstract
Rice is a typical chilling sensitive plant. Cell suspension cultures of rice also suffer injuries at chilling temperatures. However, we found out that exogenous application of ABA induces freezing tolerance in rice cell cultures in a similar manner as in other cell cultures of Gramineae plants that have genetically cold hardiness. We analyzed physiological factors involved and cytosolic proteins expressed during ABA induced freezing tolerance by 2D electrophoresis.
At the optimum conditions, the rice cells tolerated -12C and some cells even -20C after 7 days of incubation in the presence of 75 μM ABA at 25C. More than 80 CBB-stainable protein spots were either increased or induced by ABA treatment. Some of the major ABA responsive spots were detected as early as 6h of incubation with ABA containing medium while after one day incubation most ABA responsive spots were detected when the rice cells tolerated moderate freezing.
