Seventeen 'extinct' plant species back to conservation attention in Europe

Selecting the best candidates for resurrecting extinct-in-the-wild plants from herbaria

Resurrecting extinct species is a fascinating and challenging idea for scientists and the general public. Whereas some theoretical progress has been made for animals, the resurrection of extinct plants (de-extinction sensu lato) is a relatively recently discussed topic. In this context, the term 'de-extinction' is used sensu lato to refer to the resurrection of 'extinct in the wild' species from seeds or tissues preserved in herbaria, as we acknowledge the current impossibility of knowing a priori whether a herbarium seed is alive and can germinate. In plants, this could be achieved by germinating or in vitro tissue-culturing old diaspores such as seeds or spores available in herbarium specimens. This paper reports the first list of plant de-extinction candidates based on the actual availability of seeds in herbarium specimens of globally extinct plants. We reviewed globally extinct seed plants using online resources and additional literature on national red lists, resulting in a list of 361 extinct taxa. We then proposed a method of prioritizing candidates for seed-plant de-extinction from diaspores found in herbarium specimens and complemented this with a phylogenetic approach to identify species that may maximize evolutionarily distinct features. Finally, combining data on seed storage behaviour and longevity, as well as specimen age in the novel 'best de-extinction candidate' score (DEXSCO), we identified 556 herbarium specimens belonging to 161 extinct species with available seeds. We expect that this list of de-extinction candidates and the novel approach to rank them will boost research efforts towards the first-ever plant de-extinction.

Out-of-date datasets hamper conservation of species close to extinction

International databases and data aggregators on species conservation status are powerful tools supporting the efforts of conservation biologists and practitioners in reducing the loss of biodiversity. However, out-of-date information and poor interoperability of databases can hamper conservation of highly threatened species or in extreme cases can result in their removal from conservation frameworks. Lack of common standards for database updates, slow update timing and incongruencies among datasets in terms of taxonomy, threats, conservation status and holding prevent proper conservation prioritization and actions. A simple survey to solve incongruencies between the BGCI PlantSearch Database and the IUCN Red List resulted in a change of status of 16 plant species, including the 'rehabilitation' of 12 species thought to be extinct.

Re-introduction of an extinct population of Pulsatilla patens using different propagation techniques

The study focuses on the propagation of a rare and endangered plant species (Pulsatilla patens) to re-introduce an extinct population from calamine area in Southern Poland. The plants were propagated from seeds, rhizome cuttings, or regenerated in vitro from shoot tips, hypocotyls with roots or cotyledons of seedlings on Murashige & Skoog (MS) medium supplemented with 0.25 or 0.50 mg L^-1 BAP (Benzylaminopurine) via direct and indirect organogenesis or somatic embryogenesis (SE). The most efficient micropropagation method was with shoot tips as an explant on MS + 0.25 mg L^-1 BAP where 97% of the explants produced multiple shoots, mass SE was observed after transfer on ½ MS with 2% saccharose; 267 (35%) shoots rooted on ½ MS + 2% saccharose were acclimatized to ex vitro conditions. Flow cytometry revealed genome size stability of propagated plantlets. Low genetic differentiation between micropropagated plantlets and initial material was indicated by ISSR (Inter Simple Sequence Repeat) markers. Totally, 132 vigorous plantlets obtained on various pathways were introduced to the field plots in 2020; 30.33% survived the winter, and several reached the generative stage and flowered in the spring 2021. In next season (March/April 2022) the number of introduced plants decreased to 25% while the number of flowering and fruiting shoots in different clumps increased in some plots. This is the first report of successful re-introduction of the endangered P. patens based on micropropagation, rhizome cuttings, and seed germination.

Allium ducissae (A. subgen. Polyprason, Amaryllidaceae) a New Species from the Central Apennines (Italy)

In this paper, Allium ducissae (the LSID for the name Allium ducissae is: 77254606-1) is described as a new species based on morphological and molecular analyses, and its taxonomic relationships are discussed. It grows in crevices on calcareous rocks, rocky slopes and grassy ledges in the subalpine belt, within two regional protected areas in the Lazio and Abruzzo administrative regions (Central Apennines, Italy). Previously, these populations were attributed to A. strictum, a species described from Siberia, belonging to A. sect. Reticulatobulbosa. The new species is distinct from A. strictum in the morphology of vegetative and reproductive structures. Indeed, it is close to A. palentinum, an endemic species to Cantabrian Mountains (NW Spain). Both molecular and morphological data support the recognition of the Allium populations coming from the Central Apennines as a new species. Allium ducissae can be clearly distinguished from A. palentinum by longer and wider tepals, longer filaments, tooth of inner filament, flower pedicels, spathe appendage, and smaller seeds. Moreover, seed testa micro-sculptures revealed slight differences between A. ducissae and A. palentinum. Chromosome counts showed that A. ducissae is diploid with 2n = 16 chromosomes, as already known for A. palentinum. Molecular analyses support the affiliation of A. ducissae and A. palentinum to A. sect. Falcatifolia, contrary to what is known for the latter species, usually included in A. sect. Daghestanica. Finally, the IUCN assessment for the newly described species is proposed and briefly discussed.