SPECIFIC FEATURES OF CELL-INTERACTION BET WEEN WHEAT CALLUS-TISSUE AND GERMINATING UREDOSPORES OF OBLIGATE RUST FUNGUS PUCCINIA-GRAMINIS F-SP TRITICI

Specific features of development of the ectophytic stage of the rust f ungus Puccinia graminis f.sp. tritici in the callus tissue of rust-res istant and rust-susceptible wheat genotypes were studied. The callus c ells of both genotypes decrease the rate of germination of the uredosp ore germ tubes and inhibit appressorium formation after heat shock. Di rect interaction between the germ tubes and callus cells and penetrati on of the former into the extracellular space were noted. Cytoplasm ag gregation in the callus cells was observed upon interaction between th e wheat callus tissue and germ tubes and appressorium in the regions o f penetration. This shows a response of the callus cells to inoculatio n of the rust uredospores.