Selection of frost-tolerant cell lines from cell cultures of Solanum tuberosum L.

Fourteen hydroxyproline-resistant cell lines were selected by plating 7 days old cell suspensions of Solanum tuberosum L. cvs. Desiree and Maris Piper on a cell plating medium containing 5 or 10 mM hydroxyproline (hyp). Cell suspensions were either plated directly on selective media or after mutagenic treatment with gamma rays at a dose of 20 Gy or after freezing to –6°C. The frequency of resistant colonies varied from 0.15 to 0.35 x 10-6. Almost all the selected lines possessed increased levels of frost tolerance as compared to their non-selected controls except one indicating that hyp resistance and frost tolerance are not necessarily linked.