In vitro micropropagation of Primula scotica: a rare Scottish plant

Published source details Benson E.E., Danaher J.E., Pimbley I.M., Anderson C.T., Wake J.E., Daley S. & Adams L.K. (2000) In vitro micropropagation of Primula scotica: a rare Scottish plant. Biodiversity and Conservation, 9, 711-726.
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Summary

Scottish primrose Primula scotica is a rare plant endemic to northern Scotland. To date, most conservation efforts have focused on the protection of its remaining natural sites. However, biotechnological approaches may provide complementary conservation options. Here, a simple micropropagation method is reported for P.scotica.

Micropropagation technique: Source material comprised commercially available seed from which cultures were initiated after seed-surface sterilization. The micropropagation technique involves clonal proliferation of seed-derived plantlets on either hormone free tissue culture medium or on medium containing benzyl amino purine and indole acetic acid. These micropropagation methods were applied to four different clones of P.scotica and clonal differences were observed in relation to media type.

Cultures were assessed weekly for: rooting, shooting, contamination rate and hyperhydricity (a physiological disorder in plant tissue cultures characterized by high water retention capacity due to adverse culture conditions; symptoms displayed typically as 'vitrified' or 'glassy' leaf surfaces accompanied by swellings and abnormal cuticular development).

Ex vitro growth substrates: At the onset of the subsequent spring growth seasons (February–March), healthy plantlets at the 6–7 week culture stage were selected for transfer to one of five ex situ substrates. Sterilised (autoclaved) substrates were: perlite and vermiculite (J.Arthur Bower's Horticultural grade); Sorba Rods (Sigma), compost (John Innes No 1), and peat pots (Jiffy-7). The substrates were treated with half-strength hormone free basal salt medium. Nine replicate plantlets were selected for each growth substrate.

Rooting and growth: Plantlets rooted on both media types and displayed normal rosette morphology, and development proceeded via shoot and root production. Average multiplication rates of 4–6 were obtained for plants on the hormone-supplemented medium at 6 weeks old, and 1-9 for the hormone free-medium. Some plants from certain clones displayed hyperhydricity, however, this was dealt with by frequent sub-culturing intervals and transferring the plants to a hormone-free medium.

Ex vitro growth substrates: The majority of plants survived transfer to growth substrates and maintained foliar growth. However, there were notable differences in growth and health according to the substrate type and clone. Compost supported mid to prolific growth for clones 1, 2 and 4, whilst clone 3 performed better on sorbarods. The Vermiculite/Perlite mix supported poorest growth for the majority of the clones. In terms of health, for clone 4 there was little variation in status of the plants on any of the five substrates; there were wide variations between substrates observed for clone 1which grew better in sorbarods; clone 2 responded well to compost, peat pots and vermiculite.

Conclusions: The plantlets rooted on both media types and displayed normal rosette morphology. The in vitro-grown plants were successfully transferred to ex vitro conditions and subsequently established and grew on a range of growth substrates assessed for their efficacy. It is hoped to develop strategies for the reintroduction of micropropagated P. scotica plants into natural habitats in the longer-term. The simple method used successfully in micropropagation P.scotica may be applicable to other endangered Primula spp.

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