Cryopreservation of Fragaria × ananassa using different techniques

The strawberry (Fragaria spp.) is a genus of plants in the rose family. There are more than 20 named species and many hybrids and cultivars. The most common strawberries grown commercially are cultivars of the Garden Strawberry, a Fragaria × ananassa hybrid. Cultivar 'Earliglow', used in the present study, is one of the most popular, best-tasting strawberries. This excellent cultivar produces large, jewel-like, and dark red berries. Cryopreservation is important for the conservation of germplasm on long-term basis. Cryopreservation is the use of very low temperature to preserve structurally intact living cells and tissue. This method of conserving germplasm has gained wide importance in recent years with the use of tissue culture technology, cryoprotectants, and liquid nitrogen cooling. There are many different techniques and methods available. Commonly used techniques, such as encapsulation-dehydration, vitrification, etc., are based on phenomenon of vitrification. Encapsulation-dehydration is a technique which involves the formation of artificial seeds of alginate and then conservation in liquid nitrogen; whereas, vitrification involves the use of cryoprotectants, such as dimethylsulphoxide and glycerol. Use of cryo-plate is a modified way for the vitrification. Encapsulation-dehydration, vitrification, V cryo-plate and D cryo-plate methods were applied to the in vitro-grown shoot tips of Fragaria × ananassa 'Earliglow' for cryopreservation. The D cryo-plate method was found the best; where, 40% regrowth of liquid nitrogen treated plants was obtained. This was followed by vitrification, encapsulation-dehydration and V cryo-plate methods; where, post thaw recovery ranged from 0 to 15%. Fragaria shoot tip cryopreservation using D cryo-plate method was reported for the first time. The cryopreservation technique can be used for long-term conservation of Fragaria spp. including ornamental strawberry cultivars and closely related species.