Solanum commersonii Dun is a wild tuber-bearing species from Solanum genus which grows well country-wide in Uruguay and it has been demonstrated to be more adapted to local conditions than the common potato (Solanum tuberosum). Due to the reported resistance of cold temperatures and some common diseases and pests, this native specie is considered one of the most valuable genetic resources for potato breeding. We are interested in the resistance of S. commersonii against Ralstonia solanacearum, the agent responsible of bacterial wilt, which highly affect cultivated potato in Uruguay and other countries, causing important economical looses.

Breeding genetic resistance into new potato varieties using wild populations of S. commersonii is an attractive solution to this problem. While these populations should be good sources of resistance, plants within these populations might be variable, with some plants significantly more resistant than others and thus better parents for use in breeding. But if the DNA of individual plants was very uniform (as in cultivated species), resistance probably would be uniform within populations too.

Therefore, we also foccused our research in the evaluation of the genetic variability of this wild species using molecular markers. When planning DNA fingerprinting, a potential tool to analyze the biodiversity, one of the most important decisions is the marker system and technique to be used. Several different PCR techniques have been developed during the last decade, each one with specific advantages and disadvantages. The Random Amplified Polymorphic DNA (RAPD) marker technique is quick, easy and requires no prior sequence information. A single random 10-mer primer is used to specify the sequence that is to be amplified.

The correlation of the genetic variation observed in natural populations of S. commersonii and the resistance properties against R. solanacearum constitute a valuable tool for breeding programmes

María Inés Siri