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 in these conditions. Thus, there is a need to assess their longevity empirically and comparatively and to evaluate the success of alternative storage options.

METHODS

Diverse seed collections were used to assess longevity of seeds of 13 CP species stored (some for 30 years) in 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 in conventional seed bank conditions. Only some accessions stored for longer times (>25 years) showed significant signs of deterioration, with D. rotundifolia and Drosera anglica Huds. showing a time for viability to fall to 50 % (P50) in the region of other taxa considered medium/short or short lived in 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 for up to two decades. Furthermore, seedlings obtained developed normally into healthy plants when monitored for ≤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 programmes to support in situ conservation initiatives.