1. Introduction. 2. Laboratory Organization and Equipment. 3. Media Preparation. 4. Collection, Sterilization, Excision and Culture. 5. Clonal Propagation. 6. Special Cultures. 7. Secondary Metabolite Production. 8. Pathology. 9. Nitrogen Fixation. 10. Storage of Cultures. 11. Genetic Modification. 12. Epilogue. 13. References. 14. Indices.

In Vitro Culture of Trees

The forests account for 29–34% of the land area on earth (FAO, 1963). Of this area approximately 60% are gymnosperms or softwoods; some 38% are angiosperms or hardwoods, with the remaining being made up of mixed forests. While most of the harvested material is used industrially, a significant portion of the hardwoods is utilized for fuel on a worldwide basis. It is generally accepted that the forests are being harvested at a faster rate than they are being regenerated, either naturally or artificially, hence, a shortage of wood and wood products has been forecasted for the end of this century (Keays, 1974). In addition, the rapid and disastrous effects of diseases, pests, and fires may jeopardize the very existence of certain tree species. Thus, there is an urgent need for larger numbers of improved, fast-growing trees (Thorpe & Biondi, 1984). At present, the tree improvement programs underway and the clonal propagation methods available offer only limited possibilities of achieving this goal.

Application of micropropagation to forestry

Micropropagation of Woody Plants

Large-scale evaluation of plant growth in Arabidopsis thaliana by non-invasive image analysis

In 1982 the new crops research program was initiated in the Florist and Nursery Crops Laboratory to increase the diversity of florist crop germplasm in the United States. Anigozanthos, Chamelaucium, Correa, a dwarf form of Eustoma grandiflorum 'Little Blue Belle', Chamelaucium, Cupressus, and other crops have been introduced to the industry with information that describes propagation, culture, and controlled flowering. Rooting of cutting or in vitro tissue culture propagation of new crops had included Achimenantha, Chamelaucium uncinatum, 'Purple Pride', and Eustoma grandiflorum, 'Little Belle Blue', Ornithogalum dubium, Lachenalia aloides, and Lilium. In addition, a new production technology using bulbils as propagules was developed for Lilium elegans, Asiatic hybrid lily. This production technology is discussed.

Transplant Production Systems

A subculturable meristematic tissue system capable of plantlet regeneration has been developed for Pinus radiata. Multiplication was achieved by the continuous production of meristematic tissue on a modified Lepoivre medium containing 5 mg/1 BAP (LP5). This tissue has been maintained for 2.5 years to date. Meristematic nodules multiplied for one year consisted of three zones: the outer meristematic layer, a bulky layer of vacuolated cells, and friable cells containing tannins and degrading cell walls. Cavities (hollows) were often present near the center of meristematic nodules. Natural separation of meristematic nodules contributed to the multiplication process. Factors affecting the success of the system were studied because there was a large variation in response. Embryos formed shoots and multipliable meristematic tissue in similar percentages. Seedlot was not a major factor in multiplication of meristematic tissue. Half-strength LP5 medium proved best for the first 12 weeks in culture, whereas LP5 medium proved best after six months in culture. Both gelrite and liquid induced vitrification, and habituation on LP5 medium had not occurred after 20 months in culture. One of the best embryos produced 5,480 pieces of meristematic tissue in 13.5 months. In a separate experiment with the same clone, an average of 68.4 shoots elongated from each piece of tissue. It was estimated that 260,000 trees could be produced from a single, good reacting seed in 2.5 years. Genetic stability and automation, two prerequisites for commercial use, are also discussed as well as the potential for gene transfer.

Helen Davies

Papers

Multiplication of meristematic tissue: a new tissue culture system for radiata pine