RESISTANCE TO SPONGOSPORA-SUBTERRANEA IN TUBER-BEARING AND NON-TUBER-BEARING SOLANUM SPP

The incidence of infection with Spongospora subterranea was studied in the non tuber-bearing Solanum brevidens and S. etuberosum, and the tuber-bearing S. acaule, S. sucrense and S. tuberosum cvs Olympia and Pito. Shoot cuttings were grown in soil naturally infested with S. subterranea, or the roots were inoculated with a zoospore suspension. Legit models were used to analyse the data. The incidence of S. subterranea was higher in plants inoculated with zoospore suspension than in those grown in infested soil (odds ratio (OR) 10.65). Ageing the inoculum reduced the incidence of infection in the plants (OR 0.30) without altering the interspecific differences. The ORs of infection (compared to cv. Olympia) were 0.07, 0.29, 0.60 and 2.88 for S. acaule, S. sucrense, S. brevidens and S. etuberosum. Only S. acaule was significantly more resistant to infection than cv. Olympia. No infection was detected in cv. Pito.