[en] Plant pathogenesis-related proteins are toxic to invading pathogens. Among them, the Subfamily PR-1 represents low-molecular weight proteins of unknown biochemical function. Here, we describe the cloning and isolation of two PR-1 genes (PR-1b1 (GenBank accession no. SPH493450) and PR-1b2 (SPH493451)) that encode predicted basic proteins. We isolated them from Solanum phureja, a native Andean potato with horizontal resistance to late blight, caused by the oomycete Phytoplithora infestans. We demonstrate that the PR-1 genes belong to a small multigene family with an estimated copy number of 4-6 with one of them located oil chromosome IX as determined by genetic mapping. The expression of PR-1 genes was different in late blight resistant and Susceptible genotypes. Therefore, we propose that both PR-1 genes may play a role in horizontal late blight resistance of S. phureja. (c) 2006 Elsevier Ltd. All rights reserved.