The main aim of the Plant Tissue Culture Lab from the date of opening until recently was the production of virus-free rootstocks. The plant material used for micro-propagation belonged to the almond species and the initiation material was purchased virus-free from abroad. The varieties GF677 and Myrobalan 29C were propagated. The resulting thousands of rootstocks (for example around 21,000 plants of GF677 and 13,000 plants of Myrobalan 29C were produced in 2006) were used for the grafting of stone fruit trees at the government-owned nursery and the virus-free trees were sold annually in the Maltese territory. Also, ornamental plants such as the Boston ferns are being propagated in vitro.
In 2006, the activity of the Plant Tissue Culture Lab was diversified to the conservation and sustainable use of local varieties of fruit tree species which are in danger of genetic erosion. Work has already been carried out and shall be continued on the clonal and sanitary selection of local varieties of fruit trees and vines. Sanitation involves the removal of certain pests and diseases from plants by in vitro techniques. This can only be carried out using facilities like the ones at the Tissue Culture Lab. Virus-free and healthy local varieties of fruit trees and vines will then be available for conservation purposes and also for the availability of healthy stock for cultivation in Malta just in case local plants need to be utilised. Such cases include the introduction of harmful pests or diseases which may be introduced together with propagating and planting material coming from abroad.
Projects
Propagation of endangered local wild species
The following species are examples of plants which have either been worked upon by various students at the Plant Tissue Culture Laboratory or which are currently being propagated under the initiatives of the Environment Protection Directorate of the Malta Environment and Planning Authority:
Helichrysum melitense, Cremnophyton lanfrancoi, Tulipa sylvestris, Ophrys lutea, Barlia robertiana, Spiranthes spiralis, Aristolochia clusii and Sarcopoterium spinosum.
The micro-propagation of the endangered local species of orchids and tulips is currently being carried out. This is a project sponsored by HSBC under the Care for the Environment Fund. Various species of orchids such as Ophrys lutea and Barlia robertiana (Giant orchid – Orkida Kbira) and the local wild tulip, Tulipa sylvestris (Wild tulip – Tulipan Selvaġġ) were chosen for this regeneration program to prevent plants from disappearing from the Maltese archipelago. Normal propagation of these species is currently not an option. Due to the total disturbance of the orchid habitat in Malta, the only solution for safeguarding the orchid’s population is micro-propagation. Seed production is not very high even in optimum conditions and these are recalcitrant.
The material needed to start the cultures was collected from open fields with the permission of MEPA. New plantlets have been produced which are sub-cultured onto fresh medium at the required intervals. Experiments are being carried out in order to find a suitable medium for the plants to make root and for successful acclimatisation to take place. The final phase consists in the transfer of the plantlets from sterile culture vessels to a moist soil mixture where they will be kept in controlled conditions for at least four weeks before being planted in the natural habitat.
The target is to eventually have sufficient plants of each of the threatened species to be transplanted in the open environment including public and botanical gardens.
Barlia robertiana (photo by Stephen Mifsud)