Evaluation of bacterial wilt resistance on potato Somaclones derived from gamma irradiated cultures

Bacterial wilt (Ralstonia solanacearum) is an important disease of potatoes. However, the availability of genetic sources for resistance to bacterial wilt are still limited. Mutation breeding with gamma ray irradiation is a potential approach to generate genetic variability of the potato plant resistance against bacterial wilt disease. The study aimed to elucidate the resistance of potato mutants to bacterial wilt disease through in vitro and in planta evaluation. Two commercial varieties, Medians and Papita, were used as genetic materials. The apical and axillary shoots were irradiated with gamma rays at doses of 0, 30, 60, and 90 Gy. One hundred seventy-three somaclones were tested, with two original varieties (wild type), two resistant local varieties, and two diploid resistant genotypes as the controls. The evaluation was carried out in vitro in the plant tissue culture laboratory and in planta in the screenhouse. Each test was replicated 3 times and each repetition consisted of 4 explants or plants. Based on the in vitro test, 44 somaclones indicated resistance, whereas in the in planta test, 4 somaclones indicated resistance, and 22 somaclones were moderately resistant. The MannWhitney U Test shows that in vitro and in planta tests were significantly different. Meanwhile, Pearson correlation showed a weak negative correlation between the two test methods. The advance evaluation should be conducted to confirm the resistance level of selected somaclones, both from in vitro and in planta tests.