The main aim of the Plant Tissue Culture Lab within the Plant Health Biotechnology Centre at Lija, from the date of opening until recently was the production of virus-free rootstocks which were utilised for the grafting of stone fruit trees at the government-owned nursery. The grafted virus-free trees were then sold annually to Maltese growers and amateur gardeners. Also, ornamental plants such as the Boston fern and African violet have been 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. Sanitation involves the removal of certain pests and diseases from plants utilising in vitro techniques. This can only be carried out using facilities like the ones found at the Tissue Culture Lab. Virus-free and healthy local varieties of fruit trees will then be available for conservation purposes and also for the availability of healthy stock for cultivation in Malta. This will also act as a safeguard against possible loss of local varieties through the accidental introduction of harmful pests or diseases which may be introduced together with propagating and planting material coming from overseas. In addition, the Tissue Culture Lab has continued the micropropagation of ornamental plants and was also involved in the micropropagation for conservation purposes of the local tulip and various local orchids.
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)