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- Establishment of an in vitro propagation protocol for Thymus lotocephalus, a rare aromatic species of the Algarve (Portugal)Publication . Coelho, Natacha; Gonçalves, Sandra; González-Benito, María Elena; Romano, AnabelaThe aim of this work was to develop an in vitro propagation protocol for the endangered species Thymus lotocephalus using seedlings as explants. Several macronutrient concentrations of Murashige and Skoog medium (MS), cytokinin types and concentrations, and cytokinin/auxin combinations were tested to assess the shoots’ proliferation capacity. Although the best proliferation results were obtained with 6-benzyladenine, high percentages of hyperhidric shoots were observed. Because high proliferation of healthy shoots was observed in MS medium that was free of plant growth regulators, this medium was chosen for proliferation studies. The best rooting results were achieved in MS medium without auxins (92.00 ± 6.11%, 6.54 ± 0.52 and 1.60 ± 0.10 cm regarding rooting frequency, number of roots per shoot and longest roots, respectively) or supplemented with 0.5 mg l-1 indole-3-acetic acid (98.00 ± 2.11%, 11.14 ± 0.75 and 2.40 ± 0.24 cm, respectively). Plantlets were successfully acclimatised to ex vitro conditions with a survival rate of 93.33%. With the development of this micropropagation protocol, an important contribution has been made to the conservation of the endangered species T. lotocephalus.
- Germination and cryopreservation tolerance of seeds from the rare aromatic species Thymus lotocephalusPublication . Coelho, Natacha; Gonçalves, Sandra; González-Benito, María Elena; Romano, AnabelaThymus lotocephalus G. López and R. Morales is a rare aromatic species endemic from the south region of Portugal. We investigated the germination behavior and the cryopreservation tolerance of T. lotocephalus seeds collected from four populations. Seeds were set to germinate at 15 or 25 ◦C under light or darkness. The best germination temperature tested was 15 ◦C, under either light or darkness, with final germination percentages above 80% and mean germination time (MGT) below 10 days. The results showed that T. lotocephalus has non-dormant seeds. Seeds from different populations presented few differences on the final germination percentage and MGT. To assess seed tolerance to cryopreservation, they were directly immersed in liquid nitrogen for 30 days. Overall, we found that cryopreservation was non-detrimental to germination of T. lotocephalus seeds, thus being a reliable method for germplasm conservation of this endangered species.