Longevity, Cryopreservation, and Propagation of Carnivorous Plants Seeds: Insights From 13 Species in Long-Term Ex situ Collections.

Background and aims: A quarter of the assessed carnivorous plants (CPs) are threatened with extinction, and the effectiveness of ex situ conservation initiatives must be evaluated to complement in situ conservation efforts. Conventional seed storage (e.g., 15% relative humidity, -20°C) is the most common and efficient strategy for plant ex situ conservation, but seeds of diverse CPs might be short-lived at these conditions. Thus, there is a need to empirically and comparatively assess their longevity and evaluate the success of alternative storage options.

Methods: Diverse seed collections were used to assess longevity of seeds of thirteen CP species stored (some up to 30 years) at various storage conditions: ambient/uncontrolled, conventional, and cryogenic.

Key results: The relative short longevity of CP seeds stored in ambient/uncontrolled and conventional conditions was confirmed for some taxa (e.g., Drosera rotundifolia L.). Nevertheless, despite this potential short longevity, seeds of 64% of accessions tested retained their initial viability for up to two decades when stored at conventional seed bank conditions. Only some accessions stored for longer times (> 25 years), showed significant signs of deterioration, with D. rotundifolia and D. anglica Huds. showing P50 values in the region of other taxa considered medium/short or short-lived at comparable cold/dry storage conditions. As an alternative (or complement) to conventional seed banking, cryogenic storage of dry seeds was able to preserve a high germination percentage of seeds of CPs stored up to two decades. Furthermore, seedlings obtained developed normally into healthy plants when monitored up to 1.5 years after germination.

Conclusions: Despite the potential short lifespan of seeds of some CP taxa, this paper highlights and supports their routine dry storage in ex situ conservation programs to support in situ conservation initiatives.