Selection of Potato Clones Resistant to Bacterial Wilt (Ralstonia solanacearum) Disease and Evaluation of Their Genetic Diversity with RAPD

This study was carried out to select potato (Solanum tuberosum) clones resistant to Bacterial wilt (BW) disease (Ralstonia solanacearum) and evaluate genetic diversity with RAPD (Randomly amplified polymorphic DNA). A total of 440 clones collected and maintained at Highland Agriculture Research Center were tested in the hydroponic culture system with R. solanacearum race 1 and 3. After 40 days in dipping in hydroponic culture system, the resistance was evaluated as the range from 0 (resistance) to 4 (susceptible). Seventy-two clones were selected in the first screening as a resistant to race 1 or 3 in 2007, and the selected lines were tested again as the same procedure above. After the second screening, a total of 20 lines were selected as resistance to BW in 2008. For the evaluation of genetic diversity of the selected 20 clones, RAPD analysis was carried out with potato URP primer sets. From the 11 URP primers, 5 to 7 polymorphic DNA bands were amplified in selected resistant clones with each primer. With RAPD analysis, the genetic similarity was shown from 0.56 to 0.82. The selected clones were separated into two distinct groups at the genetic similarity value point of 0.56. Four clones including AG14252 were integrated into the first group, and the others, 16 clones, were grouped in the second group. In the second group, the two sub-groups showed genetic similarity value of 0.59. Seven clones including AG34326 and nine clones were separated into the first and second sub-groups, respectively. The results have revealed that bacterial wilt resistance test using hydroponic culture is favorable for the selection of BW resistant potato clones, and that RAPD analysis is useful for the identification of genetic similarity. The selected potato clones could be used as parent clones in BW resistance breeding program of potatoes.