ARS | Publication request: A reassessment of Solanum maglia in the origin of Chilean landraces of cultivated potato (Solanum tuberosum Chilotanum Group)

Submitted to: Botany
Publication Type: Abstract Only
Publication Acceptance Date: April 20, 2011
Publication Date: February 15, 2012
Citation: Spooner, D.M., Ghislain, M., Herrera, M., Montenegro, J., Clausen, A., Jansky, S.H. 2012. A reassessment of Solanum maglia in the origin of Chilean landraces of cultivated potato (Solanum tuberosum Chilotanum Group) [abstract]. Botany. Paper No. 310.

Technical Abstract: Landrace potato cultivars of Solanum tuberosum occur in two broad geographic regions; the high Andes from western Venezuela south to northern Argentina (S. tuberosum Andigenum Group), and lowland south central Chile (S. tuberosum Chilotanum Group). Chilotanum is adapted to long days, has a 241 bp plastid DNA deletion (shared with some accessions of the wild potato species S. berthaultii, but lacking in the wild potato species S. maglia) and differs morphologically by minor characters that are not always Group-specific. The modern “Irish” potato clearly originated from Chilotanum germplasm. Our research investigates the origin of Chilotanum, with one hypothesis proposing an origin from Andigenum, perhaps after hybridization with S. berthaultii; and a competing hypothesis suggesting an origin from the wild potato species S. maglia, distributed in southern Chile and adjacent western Argentina. Molecular data support both the Andean and Chilean potatoes as members of the same clade, distinct from S. berthaultii. The S. maglia hypothesis was based on morphological analyses of starch grains of extant and extinct (13,000 years before present) S. maglia, and on extant distributional data of S. maglia and Chilotanum. Our new starch grain analyses of extinct and extant S. maglia using a much wider collection of accessions of both cultivar groups of S. tuberosum show extensive overlap. In addition, we could find no evidence of sympatric distributions of extant S. maglia and Chilotanum. Therefore, starch grains and distributional data do not support this hypothesis. However, microsatellite data group all accessions of S. maglia (Argentinean and Chilean) exclusively with Chilotanum. These results could be interpreted in various ways, but all explanations have problems. One explanation is that S. maglia is either a progenitor or product of Chilotanum, but the plastid deletion of Chilotanum cannot be easily explained. Another explanation is that Chilotanum was formed by hybridization between S. berthaultii and S. maglia but this conflicts with prior cladistic analyses.