A putative viral resistance-connected protein isolated from potato cultivar sante resistant to PVYNTN infection

The causal agent of potato tuber ring necrotic disease of potato virus Y-NT N (PVYNTN) is a recently recognized and highly aggressive isolate of the PV YN strains. The protein composition of infected and control plants of some potato (Solanum tuberosum L.) cultivars that differ in their susceptibility was compared. The differences in protein patterns become visible four days after infection and pronounced two weeks alter infection. Most changes in protein composition occurred in the very sensitive cv. Igor as shown both b y SDS polyacrylamide gel electrophoresis as well as by isoelectric focusing . Nine induced proteins were clearly recognised and decrease in concentrati on of some proteins was also observed. Proteins with increased expression w ere also detected in infected tissues of virus tolerant cvs. Desiree and Pe ntland squire. Interestingly, no changes in protein expression was observed in a sample of infected potato cv. Sante which is highly resistant to the virus. However, a constitutive protein of M-app 43000 was shown to be prese nt in significantly higher concentrations compared to other cultivars. The putative resistance-connected function of this particular protein was confi rmed in another resistant cultivar - cv. Carlingford in which the amounts o f the 43000 protein are comparable to those in cv. Sante. Preparative SDS p olyacrylamide gel electrophoresis was used to isolate the protein and its N -terminal amino acid sequence was determined.