Cryotherapy in Raspberry (Rubus idaeus L.) as a Potential Method for Obtaining Virus-Free Plants and Genetic Collections

Red raspberry (Rubus idaeus L.) is a small-fruit crop of key economic importance, widely cultivated for fresh consumption and processing, and valued in traditional medicine. Vegetatively propagated material is subject to increased pathogen pressure, especially viruses, viroids, and phytoplasmas, leading to growth suppression, yield losses of up to 50%, and heightened susceptibility to secondary infections. Ensuring healthy, pathogen-free planting stock is therefore a priority in production and breeding. This review synthesizes current knowledge on cryopreservation methods applicable to raspberry, with particular emphasis on their suitability for virus eradication (shoot-tip cryotherapy) and identifies the technical parameters that determine procedural success. Cryopreservation and cryotherapy protocols based on vitrification (including variants based on plant solution vitrification and droplet vitrification) and encapsulation-dehydration were analyzed. The focus was on shoot apical meristems as the starting material and on combining cryotherapy with other sanitation procedures, for example thermotherapy. Among the available approaches, the highest post-thaw regeneration rates were obtained with vitrification protocols and with encapsulation-dehydration. Efficiency increases when cryotherapy is combined with thermotherapy. Success is strongly influenced by explant size and physiological state, preculture conditions (for example sucrose concentration), cryoprotectant composition and exposure time, and cooling and warming profiles. Beyond its role in the long-term conservation of genetic resources, cryopreservation is an effective tool for sanitizing raspberry material. Shoot-tip cryotherapy enables the production of virus-free plants, which is crucial for establishing healthy plantations and breeding programs. Incorporating standardized protocols into nursery certification systems may accelerate the dissemination of clean stock and, in the long term, reduce production losses. The evidence reviewed confirms that optimized cryopreservation protocols provide a reliable framework for both long-term conservation of germplasm and the regeneration of healthy raspberry planting material.