Somatic cell selection as a tool for developing resistance against soil-borne potato pathogen, Spongospora subterranea

Spongospora subterranea is the causal pathogen of potato powdery scab and root infection. Breeding for resistance is currently the major research focus for the management of these diseases. All methods of selection for powdery scab resistance have been achieved by conventional breeding and selection within existing potato breeding lines. This study investigates the potential of tissue culture-based somatic cell selection method to develop potato clones/lines with enhanced resistance to S. subterranea tuber and root diseases. We also attempt to investigate the link between tuber and root resistance. Potato cv. Russet Burbank was used as parent material because of its economic value and market preference. Calli were induced from the plant’s internodes and challenged with selective agents, thaxtomin and Spongospora-infected root extracts, then transferred to a recovery media and finally, shoots induced in a regeneration media. Calli in liquid media without toxin served as control treatment. Higher number of calli were recovered from non-challenged treatment (67) compared to thaxtomin (23) and root extract (10) treatment suggesting possible biological activity of these selective agents. To date, only calli recovered from the control treatment has regenerated shoots after one-month of incubation. The cell selection method was successful in recovering potentially Spongospora-resistant calli after challenge with selective agents. Pathogen screening of the regenerated shoots, from these calli, is warranted to assess resistance to Spongospora tuber and root infection and provide explanation between the link of tuber and root resistance.