Skin Color, Scab Sensitivity and Field Performance of Lines Derived From Spontaneous Chimeras of Norland Potato

On the Canadian prairies, consumers favor red-skinned potatoes (Solanum tuberosum), with Norland representing the most widely grown red-skinned cultivar. However, the skin color of Norland is not as red as desired, particularly after extended storage.  In 2004 three Norland tubers which appeared to have zones of darker skin color were discovered in University of Saskatchewan research plots.  Plants were grown from sprouts taken from both the light and dark colored zones of these tubers.   The change in skin color was stable and heritable; otherwise the plants and tubers were comparable to Norland in all other aspects.  This suggests that the color change was due to a chimeral mutation in the epidermis.  In field trials conducted in 2005 and 2006 over 30 lines derived from the chimeral tubers were assessed for skin color, yields, tuber configuration and sensitivity to scab.  Lines with acceptable yield and tuber configuration as well as enhanced scab resistance and/or superior red skin color were evaluated in replicated trials conducted from 2007-2009.   Several lines were identified that had superior red skin color relative to Norland.   When grown in fields heavily infested with both common (Streptomyces scabies) and powdery scab (Spongospora subterranea) several of the new lines also appeared more resistant to common scab than Norland.  Yield potential of the selected lines was comparable to Norland and when adjusted for grade out due to excessive scab, yields of several of the chimeral lines were superior to Norland.  This study suggests that chimeras may represent a method for rapid, low cost improvement of skin color and scab resistance of potato while maintaining desirable agronomic characteristics.