Disinfection methods to obtain axenic cultures of Posidonia oceanica seedlings germinated from beach cast fruits

Abstract The regeneration of seagrass meadows through restoration efforts relies heavily on transplantable plant material, which is currently sourced from natural populations. However, the availability of this material is limited due to the lack of established axenic micropropagation protocols, highlighting the need for further research in this area. A major challenge in Posidonia oceanica micropropagation is explant disinfection, which is essential for maintaining axenic cultures and enabling the use of media and treatments that promote tissue multiplication. This study evaluated the effectiveness of various disinfection treatments on the establishment of axenic cultures of P. oceanica seedlings germinated from beach-cast fruits at different developmental stages, providing a sustainable alternative to harvesting from natural meadows. Results showed that axenic culture success depended on seedling age, with 2-month-old seedlings achieving the highest survival (80 ± 13% at 40 weeks), compared to newly released seeds (27 ± 12% at 48 weeks) and 6-month-old seedlings (15 ± 8% at 12 weeks). The most effective disinfection protocol involved soaking 2-month-old seedlings in 0.5% sodium hypochlorite for 5 min. These findings lay the foundation for biotechnological approaches to P. oceanica restoration that reduce dependence on natural donor populations.