The importance of ex situ collections to support seed conservation of Agathis australis (kauri), a threatened tree species endemic to New Zealand

Context Agathis australis (kauri) is endemic to New Zealand (NZ) and classified as Endangered by the International Union for the Conservation of Nature. Although still the main priority, in situ conservation alone is no longer sufficient to safeguard species from extinction, especially when they are threatened by climate change and pathogens. Ex situ conservation provides opportunities to maintain plants as seeds, tissue culture or living collections in botanic gardens or germplasm repositories. Aims The current study aimed to quantify the production of viable seed in ex situ collections of A. australis growing at the Ōtari Native Botanic Garden and optimise seed banking methods. Methods Cones were collected from six specimens over 5 years and the production of viable seeds quantified. Seed germination protocols were established, the impact of desiccation assessed and the role of storage temperature (5°C, −18°C and −196°C) on seed viability evaluated. Lastly, the fatty acid profiles of fresh and stored seed were determined. Key results Viable seed production varied significantly between individual trees and years. Seeds were not desiccation sensitive but to maintain viability, it was essential to store seeds at −18°C or −196°C. Seeds had high amounts of long-chain fatty acids which increased following storage. Conclusion Ex situ collections of A. australis are a valuable tool for the development of conservation methods such as seed collection, germination and seed banking. Implications This study provides essential information to maximise the contribution of ex situ living collections for research into phenology, seed physiology and germplasm storage, which can guide integrated conservation and restoration actions for Agathis species.