Desiccation and freezing tolerance of recalcitrant seeds and embryonic axes of Prunus napaulensis (Ser.) Steud.: a crop wild relative of cherry

Prunus napaulensis (Ser.) Steud. is one of the important indigenous fruit trees of North-eastern India found in wild under niche habitat, facing immense exploitation due to its medicinally important fruits. Detailed studies on seed storage biology are required for devising appropriate ex situ and in situ conservation strategies of this species. Accordingly, desiccation and freezing tolerance were investigated in seeds and excised embryonic axes (EA) for standardizing long-term conservation through cryopreservation. The large-sized fresh seeds with 46% moisture content (MC) were found highly sensitive to desiccation, with 80% loss in viability when desiccated to 30% MC. In contrast, the freshly isolated embryonic axes (49% MC) showed remarkable tolerance when desiccated to 11% MC and yielded high recovery (81%) after cryopreservation when cultured on Murashige and Skoog medium with 0.1 mgL −1 6-benzylaminopurine and 0.05 mgL −1 naphthaleneacetic acid. Viability reduced significantly when EA were dehydrated below critical MC (11%) both in desiccated and cryopreserved embryos. Differential response of tissues in the EA was also recorded, with radical exhibiting high degree of desiccation and freezing sensitivity. Excised EA when cultured in vitro formed shoots but failed to develop roots. This study demonstrates that P. napaulensis seeds have recalcitrant storage behaviour and cryoprotection would be required for ex situ germplasm conservation.