Cryopreservation of strawberry and two aphid-transmitted strawberry viruses at different durations of PVS2 treatment

Abstract

Cryopreservation is considered to be a valuable method for long-term preservation of plant germplasm and have in recent studies also shown to be a reliable method for preserving certain plant viruses. The presented thesis studies the effect of different PVS2 durations used in cryopreservation on: (1) regeneration rate of cryopreserved strawberry cv. Korona shoot tips, and (2) survival efficiency of paid-transmitted strawberry mild yellow edge virus (SMYEV) and strawberry vein banding virus (SVBV) following cryopreservation.

Excised shoot tips of cv. Korona were cryopreserved with six different durations of PVS2 varying from 10 to 60 minutes, whereas virus-infected shoot tips were cryopreserved using either 10, 40 or 60 minutes of PVS2. The results showed that 40-60 minutes of PVS2 treatment seemed to be more efficient for preserving strawberry germplasm than lower duration times (10-30 min).

The results shows presence of SVBV in all of the regenerated shoots following cryopreservation in all the three durations of PVS2 examined. SMYEV, however, was more efficiently preserved in shoot tips exposed to 40 minutes (90%) of PVS2, in relation to 60 minutes (33%). Concentrations of the cryopreserved viruses were quantitatively analyzed by RT-qPCR.

This thesis demonstrates that SMYEV and SVBV can be successfully cryopreserved in living cells of Fragaria ssp. by droplet vitrification. The results indicates that cryopreservation has great potential in long-time preservation of both strawberry germplasm and aphid-transmitted strawberry-infecting viruses.