Effect of blasticidin S on development of potential of potato tuber cells to react hypersensitively to infection by Phytophthora infestans

Abstract

It was reported previously that the hypersensitive death of surface cells of discs infected by the incompatible race 0 of Phytophthora infestans occurred late, when inoculated soon after preparation (cutting) of the discs. When other discs were inoculated 17 to 20 h or more after cutting, on the contrary, hypersensitive cell death occurred very quickly. These results indicated that the cells at the cut surface lack the ability to undergo immediate hypersensitivity, but they acquire this ability by 20 h after cutting. When tuber discs were treated with 10 parts/10 6 of blasticidin S (BcS) for 3 h beginning 3 h after cutting, the cells did not acquire the potential to react hypersensitively. This indicated that de novo protein synthesis was necessary for cells of the cut surface of tubers to acquire this potential. On the contrary, treatment with BcS had no effect on the potential, when the treatment was done after the potential had been allowed to build up after cutting. However, hypersensitive cell death in tissues which were treated with BcS 20 h after cutting was delayed when inoculation with incompatible race 0 was made 14 h after BcS treatment. Potato cells infected by compatible race 1 survived for a long time. In this case, too, cell death was greatly delayed by treatment with BcS, resulting in an increase in aerial mycelium and spores production. This suggested that de novo protein synthesis is not necessary for the establishment of a compatible relation between the host and the parasite.