Does light spectral quality affect survival and regeneration of potato (Solanum tuberosum L.) shoot tips after cryopreservation?

Cryopreservation, the storage of germplasm at ultra-low temperature is the most reliable tool for long-term preservation of plant genetic resources. Cryopreservation techniques are widely applied but the effect of light spectra on plant recovery after cryopreservation is largely unknown. Therefore, we investigated the effect of different light spectral qualities on survival and regeneration of shoot tips of potato (Solanum tuberosum L.) cultivars Agrie Dzeltenie, Maret, Bintje, D,sir,e and Anti cryopreserved by the DMSO-droplet method. Prior to cryopreservation, the plants were stored under cool white fluorescent light (CW). Post-cryopreservation, the plants were allowed to regenerate under six different light qualities: CW, warm white light (HQI), blue LEDs (B), red LEDs (R), red with 10 % of blue (RB) and RBF - red with 10 % of blue with addition of 20 % of far-red LEDs. The light spectral quality had a significant effect on the survival and regeneration of potato shoot tips after cryopreservation. The combination of red light with 10 % of blue (RB) doubled the regeneration percentage of all cultivars, whereas red light (R) was not suitable for regeneration after cryopreservation. Specifically, the regeneration percentages were increased in RB compared to CW from 25.5 to 52.6 % for 'Agrie Dzeltenie', 25.0-43.6 % for 'Maret', 8.1-26.1 % for 'Bintje', 0.0-17.1 % for 'Anti' and 18.2-36.6 % for 'D,sir,e'. Therefore, the modification of light spectra during the recovery phase is a promising tool for increasing the regeneration of potato shoot tips after cryopreservation.