NEAR-ISOGENIC WHEAT SUSPENSION-CULTURES - ESTABLISHMENT, ELICITOR INDUCED PEROXIDASE-ACTIVITY AND POTENTIAL USE IN THE STUDY OF HOST PATHOGEN-INTERACTIONS

Callus and suspension cultures were established from two near-isogenic lines of Triticum aestivum, cultivar Prelude, resistant and susceptible to stem rust. The cultures were characterized with respect to growth kinetics, pH, nutrient uptake, protein and peroxidase secretion into the culture medium. Among other differences, higher extracellular peroxidase activities were observed in the resistant line. These differences in peroxidase activity were even more obvious when the suspension cultures were treated with elicitor-active materials that included Pgt-elicitor isolated from stem rust germ tubes. Treatment with Pgt-elicitor resulted in a significant increase in extracellular peroxidase activity in suspension cultured cells originating from the resistant wheat line, while the culture originating from the susceptible wheat line was not affected. Remarkably, chitinoligomers, chitosan and DEAE-dextran stimulated peroxidase activity in both cell cultures. Further investigations using gel electrophoresis revealed that in addition to some anionic isoperoxidases mainly cationic isoperoxidases respond to elicitors. The results suggest that the cell cultures provide a suitable system to investigate biochemical and molecular biological aspects of the wheat/rust-interaction, including the mode of elicitor action.