Light spectrum modulates stress and defense gene expression in potato (Solanum tuberosum L.) shoot tips during post-cryopreservation recovery

Light intensity and spectral quality are two important factors that affect the cryopreservation success of plant germplasm. In a previous study, we found that LEDs with 90% red and 10% blue (RB) light have a positive effect on potato (Solanum tuberosum L.) shoot tip recovery during post-cryopreservation regeneration. In the present study, transcriptome profiles of non-cryopreserved (-) and cryopreserved (+) potato shoot tips exposed to RB, cool white fluorescent tubes (CW) and full darkness (D) were compared. Results indicated that light spectrum significantly affects transcript numbers in post-cryopreserved samples resulting in 3,284 differentially expressed genes of recovering shoot tips exposed to CW, RB and D. Gene ontology (GO) enrichment analysis revealed that several stress-related terms were more abundant in CW+, whereas morphogenesis-related processes were activated under RB+. Overall, cryopreservation had an extensive effect on gene expression, as 12,017 genes were differentially expressed in non-cryopreserved and cryopreserved shoot tips. Among all cryopreserved samples, enriched GO terms included various defense and stress responses to biotic stimuli and oxidative stress, whereas suppressed responses were mainly related to organ morphogenesis. The present study emphasizes that the optimization of light spectral properties to decrease light-related stress may greatly benefit the cryopreservation efficiency of plant germplasm. Overall design: Comparison of non-cryopreserved in vitro potato shoot tips to cryopreserved shoot tips during recovery under cool white fluorescent, mixture of red and blue LEDs and complete darkness.