MOLECULAR VERIFICATION OF RELEASED POTATO MUTANTS RESISTANT TO Ralstonia solanacearum UNDER CONSEQUENT PATHOGEN STRESS

In vitro cultured nodal segments of three potato cultivars namely, Diamant, Spunta and Cara were irradiated with 9 doses of gamma radiation (5, 10, 20, 30, 40, 50, 60, 70 and 80 Gy) with control. Cv. Diamant showed the highest number of survival shoots. Under artificial infection with Ralstonia. solanacearum, all in vitro plantlet populations of the three genotypes were susceptible except two mutant derived from Diamant and one from Spunta which showed resistant phenotype. The progenies of the putatively resistant lines were grown in naturally infested field and assayed by a latest developed specific and rapid real-time PCR for detecting R. solanacearum in soil and plant tissues using the specific primers RS SA2. The released lines surpassed their original cultivars for all studied agronomic traits, furthermore, qPCR analyses revealed that progeny of one of the released lines were considered negative based on our cut off Ct value of 0.0.