Overcoming sexual sterility in conservation of endangered species: the prominent role of biotechnology in the multiplication of Zelkova sicula (Ulmaceae), a relict tree at the brink of extinction

  • Angela CarraEmail author
  • Caterina Catalano
  • Ornella Badalamenti
  • Francesco Carimi
  • Salvatore Pasta
  • Antonio Motisi
  • Loredana Abbate
  • Francesca La Bella
  • Laurence Fazan
  • Gregor Kozlowski
  • Giuseppe Garfì
Original Article


Biotechnology provides valuable tools to support conservation of plant species, especially in case of threatened taxa or when dealing with seed unavailability, low viability or sterility. However, plant cell culture methods have often to face problems associated with tissue recalcitrance to in vitro systems. Recalcitrance can be related to a variety of triggering factors, involving many efforts and manipulations within one or more of the micropropagation stages before obtaining successful results. An in vitro propagation protocol was developed for Zelkova sicula, a very rare and endangered relict tree, endemic to Sicily (Southern Italy). The species revealed extremely recalcitrant to in vitro culture approaches, but after many trials throughout a number of years an effective micropropagation protocol was completed. The rooting rate was about 84% of the treated explants, 8% of which were successfully acclimatized outdoor and reintroduced in the wild within a comprehensive conservation project. The technique allowed to overcome the problems of sexual sterility of this species, hence contributing concretely to contrast the problems connected with its conservation. However, additional efforts need to be carried out in order to refine the acclimatization step and further improve the whole process effectiveness.

Key Message

A micropropagation protocol was developed for the rare and endangered tree species Zelkova sicula. The in vitro procedure allowed to overcome seed sterility providing a plant stock successfully reintroduced in the wild.


Axillary buds Clonal species Ex vitro acclimatization In vitro propagation Recalcitrance Threatened species 



The results of this work are part of the activities funded by the Programme LIFE+, Project LIFE10 NAT/IT/000237 Zelkov@zione ( The authors are also grateful to the Fondation Franklinia for its valuable support.

Author contributions

AC, GG, LF and GK conceived the paper. LA, AC, CC, OB, FLB and AM designed and performed the in vitro experiments. AC, FC and GG supervised all the experiments. AC, CC, FC, SP and GG wrote the manuscript. All authors contributed to the discussions and approved the final manuscript.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


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Copyright information

© Springer Nature B.V. 2019

Authors and Affiliations

  1. 1.Institute of Biosciences and BioResourcesNational Research CouncilPalermoItaly
  2. 2.Department of Biology and Botanic Garden, Unit of Ecology and EvolutionUniversity of FribourgFribourgSwitzerland
  3. 3.Natural History Museum FribourgFribourgSwitzerland

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