The potato ontology is part of a community effort to establish a set of related crop ontologies. The advantage of an ontology is that both humans and software applications can understand a data domain. This will allow the application of numerical or data mining techniques that may help to uncover previously unknown correlations. Building on previous draft versions, here we focus on traits important to breeding: we identified so far 70 descriptors. These include: morphological (36), agronomical performance (7), resistance traits (7), biochemical (6), reaction to abiotic stresses (2), molecular (1 ) and post-harvest (9). We anticipate further refinements and cross-checks.