Studies on Seed Germination and Micropropagation of Clinopodium nepeta: A Medicinal and Aromatic Plant

Abstract

<jats:p>Seed ecophysiology and micropropagation of <jats:italic>Clinopodium nepeta,</jats:italic> an aromatic Mediterranean plant with pharmaceutical and horticultural uses was investigated. The optimum germination temperature of seeds stored at room temperature for 0, 6, or 12 months was 15 to 20 °C (100% germination completed in 10 to14 days) and cardinal temperatures were defined at 10 and 30 °C (80% to 82% and 62% to 76% germination, respectively). Six or 12 months of storage did not seem to affect germination, although 12-month-old seeds germinated at higher percentage and completed germination earlier at 15 °C than at 20 °C. Concerning micropropagation, shoot multiplication at subcultures of both adult plant- and seedling-origin nodal explants was tested on Murashige and Skoog (MS) medium supplemented with various cytokinin types, i.e., zeatin (ZEA), 6-benzyladenine (BA), kinetin (KIN), and 6-γ-γ-(dimethylallylamino)-purine (2IP), at various concentrations from 0.0 to 8.0 mg·L<jats:sup>−1</jats:sup>. Both explant types presented a rather similar response during in vitro culture. Increasing concentration of all cytokinin types resulted in an increase in shoot number per responding explant (1.1–5.3) and in most cases a decrease in shoot length (0.6–3.4 cm). Increasing cytokinin concentration induced hyperhydricity to a number of shoots (0.1–6.5) per explant, mostly when ZEA and BA were used. Supplementing the MS medium with 8.0 mg·L<jats:sup>−1</jats:sup> BA combined with 0.1 mg·L<jats:sup>−1</jats:sup> 1-naphthaleneacetic acid (NAA) led to almost elimination of hyperhydricity and very satisfactory shoot production (80%/88% explant response and 6.5/7.5 shoot number per responding explant for seedling- / adult-origin explants, respectively). Alternatively, increasing the agar concentration to 12.0 g·L<jats:sup>−1</jats:sup> and supplementing the medium with 8.0 mg·L<jats:sup>−1</jats:sup> BA only, resulted in the same effect on eliminating hyperhydricity, such as the addition of NAA, and in the best shoot multiplication response achieved in this study (100% explant response, 9.4/9.9 shoots per explant for seedling-/adult-origin explants, respectively). Microshoots rooted abundantly (92% to 100%) on half-strength MS medium, either Hf or supplemented with 0.5 mg·L<jats:sup>−1</jats:sup> to 4.0 mg·L<jats:sup>−1</jats:sup> indole-3-butyric acid (IBA). The addition of IBA to the rooting medium, regardless of its concentration, affected only the root length by increasing it 2- to 3-fold. Microshoot clusters produced on multiplication media rooted at 96% when cultured on Hf half-strength MS medium. Rooted microshoots and shoot clusters survived at 80% to 100%, respectively, after ex vitro acclimatization in peat:perlite 1:1 (v/v).</jats:p>

Seed germination, micropropagation from adult and juvenile origin explants and address of hyperhydricity of the Cretan endemic herb Calamintha cretica

“…Germination percentages achieved were very high, similar to those we found for the close related species Calamintha nepeta (Vlachou et al, 2019), although other researchers have reported lower germination performances for the latter (Benvenuti and Bacci, 2010;Casalini et al, 2017). The high germination observed soon after seed harvest and for at least one year after, without any seed pretreatment, indicates absence of dormancy, something that characterizes relative species as well, i.e.…”

“…The high germination observed soon after seed harvest and for at least one year after, without any seed pretreatment, indicates absence of dormancy, something that characterizes relative species as well, i.e. C. nepeta (Vlachou et al, 2019), C. vulgare (Angelova et al, 1994) and C. sandaliotica (Mattana et al, 2016), a number of other Lamiaceae plants of Crete Origanum dictamnus, Sideritis syriaca ssp. syriaca, Salvia pomifera ssp.…”

Chemical Composition, Antifungal and Insecticidal Activities of the Essential Oils from Tunisian Clinopodium nepeta subsp. nepeta and Clinopodium nepeta subsp. glandulosum

“…nepeta and subsp. glandulosum [30,32]. However, according to some authors, the chemical composition is independent of the subspecies nepeta or glandulosum as both constitute common sources of terpenoids and may produce the same major volatiles with the C-3 oxygenated p-menthane skeleton [33,38].…”

“…nepeta leaves have been used as a fragrance and insect repellent [29]. The essential oils from the subspecies collected in Portugal, Serbia and Italy have been characterized for antifungal, antiproliferative, antioxidant, and antimicrobial effects [30][31][32][33]. In Tunisia only two subspecies, namely C. nepeta subsp.…”

Comparative study of polyphenolic content and antioxidant capacity in fruits of Arbutus unedo, A. andrachne and their natural hybrid A.× andrachnoides

“…Native plants from the wild, i.e. representative xerophytic species of the Mediterranean basin, with both ornamental characteristics and nutraceutical properties are of high importance and they are introduced more and more in the urban and suburban landscape apart from being used in landscape restorations and reforestations (Papafotiou and Martini, 2016;Vlachou et al, 2019). Ericaceae family, involves widespread members well known for their pharmaceutical effects (Pavlović et al, 2009).…”