A new economical storage technique for strawberry (Fragaria x ananassa Duch.) in vitro

Strawberry plants grown in vitro are typically stored and maintained on agar containing Murashige and Skoog (MS) media and sucrose as a carbohydrate source. This method of storing strawberry plants in vitro is expensive and time consuming, requiring sub-culturing onto fresh media every 2 to 3 mo. This study aimed to establish the viability of using a substrate alternative as an economical replacement for MS media, for both long-term storage in vitro and ease of transfer (ex vitro). A protocol was developed for strawberry in vitro using commercially available sterilized peat pellets (Jiffy-7 (R) pellets), to optimize culture conditions and tissue culture practices. Suitability of the peat substrate was measured by the plant's overall response to culture in vitro and subsequent health and survival ex vitro following deflasking. Included in this study was a comparison of the use of vented vs non-vented tissue culture vessels for their effect on plant development and survival in vitro and ex vitro. The results show that strawberry plants can be grown and stored under in vitro conditions in vented vessels without sub-culturing for up to 3 yr or more. This equates to an approximately eightfold more efficient technique, significantly decreasing cost of storing and maintaining strawberry plants in vitro. Furthermore, plants grown in the peat substrate did not multiply, and had more established secondary roots than those grown in the conventional MS media.