Plant Health Laboratories

Plant Tissue Culture Laboratory

The main mission 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 belongs 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.

Plant Tissue Culture

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. Accessions of local ecotypes of peaches that are being kept at the Plant Biotechnology Centre shall undergo assessment to confirm their sanitary status. If infected plants are found, sanitation is carried out by heat therapy and in vitro culture. These virus-free plants shall be used for the establishment of a national fruit tree genebank. Also, mother plants may be established which can then be utilised for the production of certified fruit trees. The resulting fruit trees can then be given to farmers.

In connection with this activity, a virus-elimination trial was started in December 2006. Cultivars were selected for the sanitation process and represent the whole collection. In vitro culture of selected varieties was initiated. Meristems were isolated from buds and planted on a medium. It is planned that after three months, the surviving shoots after propagation will be tested for the presence of quarantine viruses and viroids. To complete the project, it will take about 300 days.

Projects

Endangered local Ophrys, Barlia and Tulipa species

The micro-propagation of the endangered local species of orchids and tulips is currently being carried out by an adviser at the Tissue Culture Lab. This is a project sponsored by HSBC under the Care for the Environment Fund. Three plants, Ophrys lutea, Barlia robertiana (Giant orchid – Orkida Kbira) and 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. Following the conclusion of the first phase of research, experiments are being carried out to establish a suitable micro-propagation technique. The creation of new intact plantlets will be achieved in the first phase. The growing shoots shall later be subdivided and sub-cultured onto fresh nutrient media at intervals of two or three weeks. This will be followed by the process of elongation and in vitro root development which will prepare the plantlets for establishment in the soil. 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 open.

The target is to have sufficient plants of each of the threatened species to be transplanted in the open environment including public and botanical gardens, within two years (2006 - 2007).

Barlia robertiana (photo by Stephen Mifsud)

Endangered local Aristolochia and Sarcopoterium species

Another project sponsored by MEPA is being carried out on the local Aristolochia clusii and Sarcopoterium spinosum. These plants have been micro-propagated and good results are being achieved as a considerable number of plants are now growing and are being maintained in the shadehouse and glasshouse at the Plant Biotechnology Centre. These plants shall be planted in various localities in the Maltese Islands.

Sarcopoterium spinosum in vitro

Aristolochia clusii acclimatised in vivo

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