A simple method to establish an efficient medium suitable for potato regeneration.

Potato (Solanum tuberosum) is one of the important crop plants, and many potato cultivars consist of a tetraploid genome with high heterozygosity. The techniques of transformation and genome editing require plant regeneration. However, no efficient regeneration method has been established except for some specific cultivars, such as 'Sayaka'. In general, it is necessary to determine the adequate concentrations of auxin and cytokinin for plant regeneration. We established an efficient method using a 24-well microplate that easily enabled determination of the concentrations of these plant growth regulators suitable for shoot regeneration. Using this method, the optimal concentrations of these factors were analyzed for two representative potato cultivars, 'Sayaka' and 'Konafubuki'. This analysis revealed there was a large difference in the optimal concentrations between them. Based on this result, a specialized medium for the efficient regeneration of 'Konafubuki' cultivars was proposed. This assay method was also applied for determination of hygromycin sensitivity of these potato cultivars, and it was observed that 'Konafubuki' was rather sensitive to hygromycin. These findings suggested that the selection of a 'Konafubuki' transformant could be achieved using a medium containing a lower amount of hygromycin than that used for 'Sayaka'.