Carl-Henrik Lensjø Alvin

Abstract

Background of the study – Cryopreservation is considered to be a valuable method for long-term preservation of plant germplasm and recently it has been shown to be a reliable method for preserving obligate pathogens including plant viruses. Objectives – (1) Droplet-vitrification cryopreservation of strawberry genotypes in Norway; (2) Preservation efficiency of aphid-transmitted strawberry mild yellow edge virus (SMYEV) and strawberry vein banding virus (SVBV) following cryopreservation. Methods – Excised shoot tips of cv. ‘Korona’ were cryopreserved with different durations of PVS2 varying from 10 to 60 min, whereas virus-infected shoot tips were cryopreserved using either 10, 40 or 60 min of PVS2. Results – The results showed that 40–60 minutes of PVS2 treatment was more efficient for preserving strawberry germplasm than lower duration times (10–30 min). Thirty-two strawberry genotypes have been successfully cryopreserved through droplet-vitrification with regeneration rates ranging from 45% to 100% with 40 min PVS2 treatment. Cryopreserved viruses were quantitatively analyzed by Reverse Transcription-quantitative polymerase chain reaction (RT-qPCR). SVBV was successfully cryopreserved in all the regenerated shoots following cryopreservation with all the three durations of PVS2 examined. SMYEV, however, was more efficiently preserved in shoot tips exposed to 40 min (90%) of PVS2, in comparison to 60 min (33%). Conclusion – This demonstrates that SMYEV and SVBV can be successfully cryopreserved in living cells of Fragaria ssp. by droplet vitrification. The results indicate that cryopreservation has great potential for long-time preservation of both strawberry germplasm and aphid-transmitted strawberry-infecting viruses.