Seed germination and vegetative and in vitro propagation of Hieracium lucidum subsp. lucidum (Asteraceae), a critically endangered endemic taxon of the Sicilian flora

Valeria Gianguzzi; Emilio Di Gristina; Giulio Barone; Francesco Sottile; Gianniantonio Domina

doi:10.7717/peerj.16839

Seed germination and vegetative and in vitro propagation of Hieracium lucidum subsp. lucidum (Asteraceae), a critically endangered endemic taxon of the Sicilian flora

PeerJ. 2024 Feb 9:12:e16839. doi: 10.7717/peerj.16839. eCollection 2024.

Authors

Valeria Gianguzzi¹, Emilio Di Gristina¹, Giulio Barone^{1

2}, Francesco Sottile³, Gianniantonio Domina^{1

2}

Affiliations

¹ Department of Agricultural, Food and Forest Sciences (SAAF), University of Palermo, Palermo, Italy.
² NBFC, National Biodiversity Future Center, University of Palermo, Palermo, Italy.
³ Department of Architecture, University of Palermo, Palermo, Italy.

Abstract

Hieracium lucidum subsp. lucidum is a critically endangered endemic taxa of the Sicilian flora. It is a relict of the Tertiary period surviving on the cliffs of Monte Gallo (NW-Sicily). This research focused on finding the best protocols for seed germination and vegetative and in vitro propagation to contribute to ex situ conservation. Seed germination tests were carried out using constant temperatures of 15 °C, 20 °C and 25 °C in continuous darkness and an alternating temperature of 30/15 °C (16 h/8 h, light/dark). The seeds had no dormancy, and a high germination capacity (70-95%) was obtained at all tested thermoperiods. The possibility of vegetative propagation of the taxon was evaluated through the rooting capacity of stem cuttings treated or not treated with indole-3-butyric acid (IBA). All cuttings were treated with IBA rooted within 2 months, while only 50% of the untreated cuttings were rooted within a longer time. An efficient protocol for rapid in vitro propagation from leaf portions was developed. The response of explants was tested on hormone-free Murashige and Skoog (MS) basal medium and MS enriched with different types of cytokinins: 6-Benzylaminopurine (BAP) and meta-Topolin (mT) in combination with naphthaleneacetic acid (NAA) and 2,4-Dichlorophenoxyacetic acid (2,4-D) at the same concentration. The combination of mT (2 mg L^-1) and 2,4-D (1 mg L^-1) in the medium was the most effective and showed the highest percentage of callus induction and the mean number of regenerated shoots. The maximum rate of root regeneration and the maximum number and length of roots were obtained on hormone-free MS and MS enriched with IBA at concentrations of 1 mg L^-1. From the results obtained, it can be concluded that H. lucidum subsp. lucidum can be successfully propagated using one of the tested techniques, subject to the availability of the material for reproduction.

Keywords: Conservation; Endemism; Leaf explants; Mediterranean flora; Sexual reproduction; Vegetative multiplication.

MeSH terms

2,4-Dichlorophenoxyacetic Acid
Asteraceae*
Cytokinins
Germination* / physiology
Seeds

Substances

Cytokinins
2,4-Dichlorophenoxyacetic Acid

Grants and funding

This work was supported by NBFC to the University of Palermo, funded by the Italian Ministry of University and Research, PNRR, Missione 4 Componente 2, “Dalla ricerca all’impresa”, Investimento 1.4, Project CN00000033, by the “Progetto di Ricerca di Rilevante Interesse Nazionale” (PRIN) “PLAN.T.S. 2.0–towards a renaissance of PLANt Taxonomy and Systematics” led by the University of Pisa, under the grant number 2017JW4HZK, and by “Fondo per il Finanziamento della Ricerca di Ateneo” (FFR 2022 E. Di Gristina, University of Palermo). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.