Trevor A. Thorpe

Plant cell and tissue culture.

Part A: 1. Initiation, Nutrition and Maintenance of Plant Cell and Tissue Cultures F. Constabel. 2. Morphogenesis and Regeneration T.A. Thorpe. 3. Meristem and Shoot Tip Culture: Requirements and Applications N.S. Nehra, K.K. Kartha. 4. Plant Protoplasts for Cell Fusion and Direct DNA Uptake: Culture and Regeneration Systems A. Fehrer, D. Dudits. 5. Isolation and Characterisation of Mutant Cell Lines P.J. Dix. 6. Origins, Causes and Uses of Variation in Plant Tissue Cultures A. Karp. 7. Production and Use of Isogenic Lines G. Wenzel, B. Foroughi-Wehr. 8. In vitro Methods for the Control of Fertilization and Embryo Development V. Raghavan. 9. Cryopreservation and Germplasm Storage K.K. Kartha, F. Engelmann. 10. Plant Transformation M.A.W. Hinchee, D.R. Corbin, C.L. Armstrong, J.E. Fry, S.S. Sato, D.L. Deboer, W.A. Petersen, T.A. Armstrong, D.V. Connor-Ward, J.G. Layton, R.B. Horsch. 11. Cell Culture for Production of Secondary Metabolites F. Constabel, R.T. Tyler. Part B: 12. In vitro Culture of Cereals and Grasses I.K. Vasil, V. Vasil. 13. In vitro Culture of Legumes M.R. Davey, V. Kumar, N. Hammatt. 14. In vitro Culture of Vegetable Crops J.F. Reynolds. 15. In vitro Culture of Potato M.G.K. Jones. 16. In vitro Culture of Root and Tuber Crops A.D. Krikorian. 17. In vitro Culture of Oilseeds C.E. Palmer, W.A. Keller. 18. In vitro Culture of Temperate Fruits R.H. Zimmerman, H.J. Swartz. 19. In vitro Culture of Tropical Fruits J.W. Groisser. 20. In vitro Culture of Plantation Crops A.D. Krikorian. 21. In vitro Culture of Forest Trees I.S. Harry, T.A. Thorpe. 22. In vitro Culture of Ornamentals P. Debergh. Index.

In vitro embryogenesis in plants.

1. In vitro embryogenesis: Some historical issues and unresolved problems W. Halperin. 2. Asexual embryogenesis in vascular plants in nature K.K. Sharma, T.A. Thorpe. 3. Zygotic embryogenesis in gymnosperms and angiosperms V. Raghavan, K.K. Sharma. 4. Culture of zygotic embryos M. Monnier. 5. Morphogenic aspects of somatic embryogenesis S.A. Merkle, W.A. Parrott, B.A. Flinn. 6. Structural and developmental patterns in somatic embryogenesis E.C. Yeung. 7. Physiology and biochemistry of somatic embryogenesis K. Nomura, A. Komamine. 8. Molecular biology of somatic embryogenesis D. Dudits, J. Gyorgyey, L. Bogre, L. Bako. 9. Haploid embryogenesis A.M.R. Ferrie, C.E. Palmer, W.A. Keller. 10. Somatic embryogenesis in herbaceous dicots D.C.W. Brown, K.I. Finstad, E.M. Watson. 11. Somatic embryogenesis in herbaceous monocots S. Krishna Raj, I.K. Vasil. 12. Somatic embryogenesis in woody plants D.I. Dunstan, T.E. Tautorus, T.A. Thorpe. Index.

Plant tissue culture media

Plant tissue culture techniques have become vitally important for pursuing a wide range of fundamental and applied problems in research and development. The techniques encompass a variety of procedures used for specific purposes. The growing of masses of unorganized cells (callus) on agar or in liquid suspension is widely employed in biochemical and growth studies (1-5). The culture of segments of stems, roots, leaves or of callus provides systems to study differentiation, morphogenesis and plant regeneration (6, 7). Shoot apex culture methods leading to plant regeneration have been adopted for plant propagation and production of virusfree stock (8). The culture of anthers and pollen provides new approaches to haploid plant formation (9). Recently the technology has been extended to include the isolation and culture of plant protoplasts which are employed in fusion and somatic cell hybridization (10-13). The development of the various types of tissue culture has been based on empirical approaches, and some of the observations recorded in the literature may not be typical for plant cells. Differences in medium, environment, age, cell origin, and growth rates may explain the behavior of a particular line and need not represent a general characteristic of plant cells in culture. More uniformity in conditions of culture would assist in making data and observations more comparable.

Plant hormones and plant growth regulators in plant tissue culture

SummaryThis is a short review of the classical and new, natural and synthetic plant hormones and growth regulators (phytohormones) and highlights some of their uses in plant tissue culture. Plant hormones rarely act alone, and for most processes— at least those that are observed at the organ level—many of these regulators have interacted in order to produce the final effect. The following substances are discussed: (a) Classical plant hormones (auxins, cytokinins, gibberellins, abscisic acid, ethylene and growth regulatory substances with similar biological effects. New, naturally occurring substances in these categories are still being discovered. At the same time, novel structurally related compounds are constantly being synthesized. There are also many new but chemically unrelated compounds with similar hormone-like activity being produced. A better knowledge of the uptake, transport, metabolism, and mode of action of phytohormones and the appearance of chemicals that inhibit synthesis, transport, and action of the native plant hormones has increased our knowledge of the role of these hormones in growth and development. (b) More recently discovered natural growth substances that have phytohormonal-like regulatory roles (polyamines, oligosaccharins, salicylates, jasmonates, sterols, brassinosteroids, dehydrodiconiferyl alcohol glucosides, turgorins, systemin, unrelated natural stimulators and inhibitors), as well as myoinositol. Many of these growth active substances have not yet been examined in relation to growth and organized developmentin vitro.

Purine and pyrimidine nucleotide metabolism in higher plants.

Purine and pyrimidine nucleotides participate in many biochemical processes in plants. They are building blocks for nucleic acid synthesis, an energy source, precursors for the synthesis of primary products, such as sucrose, polysaccharides, phospholipids, as well as secondary products. Therefore, biosynthesis and metabolism of nucleotides are of fundamental importance in the growth and development of plants. Nucleotides are synthesized both from amino acids and other small molecules via de novo pathways, and from preformed nucleobases and nucleosides by salvage pathways. In this article the biosynthesis, interconversion and degradation of purine and pyrimidine nucleotides in higher plants are reviewed. This description is followed by an examination of physiological aspects of nucleotide metabolism in various areas of growth and organized development in plants, including embryo maturation and germination, in vitro organogenesis, storage organ development and sprouting, leaf senescence, and cultured plant cells. The effects of environmental factors on nucleotide metabolism are also described. This review ends with a brief discussion of molecular studies on nucleotide synthesis and metabolism.

Application of micropropagation to forestry

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.

Somatic embryogenesis and plantlet regeneration in cultured immature embryos of Picea glauca

Summary Somatic embryogenesis and plantlet regeneration was obtained from cultured immature embryos of Picea glauca (Moench) Voss (white spruce) on a modified von Arnold and Eriksson’s (1981) medium supplemented with N 6 -benzyladenine and one of the auxins: 2,4-dichlorophenoxyacetic acid, 2-methyl-4-chlorophenoxyacetic acid or 4-amino-3, 5, 6-trichloropicolinic acid (picloram). Picloram at 5 or 10 μM was the most effective auxin. The optimum size of immature embryo for initiation of embryogenic callus and somatic embryos was found to be 1.5–2 mm. Increasing the osmolarity of the medium and reducing the concentration of 2,4-D enhanced development and maturation of the somatic embryos. Comparison of the growth of plantlets on different basal media showed that the best growth occurred on one-third strength Schenk and Hildebrandt’s (1972) medium.

Maturation of somatic embryos in conifers: Morphogenesis, physiology, biochemistry, and molecular biology

SummaryIn the past 15 years tremendons progress has been made towards the development of systems for the induction and development of somatic embryos of coniferous species. Since the first report in 1985, several species have been induced to produce somatic embryos. This has been rendered possible by the development of rational media and improvement of culture conditions, which have resulted in increased embryo quality and higher conversion frequency. Understanding the physiological and biochemical events occurring during in vivo embryogenesis has been fundamental in the design of new protocols for improving the somatic embryogenic process. Specifically, the inclusions of abscisic acid (ABA) and osmotic agents, such as polyethylene glycol (PEG), have been shown to be necessary for the functional development of somatic embryos. In the past few years, physiological and biochemical investigations have been useful in increasing our knowledge on the mode of action of ABA and PEG during embryo development. In comparison with the flowering plants, our understanding on the molecular mechanisms regulating the embryogenic process in coniferous species is still very limited. The application of new molecular techniques is therefore fundamental towards this end. The emphasis of this review is on recent information dealing with the maturation of conifer somatic embryos.

Shoot Histogenesis in Cotyledon Explants of Radiata Pine

The histological events associated with shoot primordium formation in cultured excised cotyledons from germinated seed of radiata pine (Pinus radiata D. Don) were examined. Cytological changes in the explants were observed by day 1 in culture. Mitotic activity, initially random, became restricted to the epidermal and subepidermal cell layers closest to the medium. This led to the formation of meristematic tissue along the entire length of the cotyledon during the first 3 wk in culture. Within this meristematic zone, meristemoids, shoot primordia, and finally shoots with well-developed apical meristems, needles, and needle primordia were formed.

Starch Accumulation in Shoot-Forming Tobacco Callus Cultures

Microscopic histochemical examinations of cultured tobacco callus disclosed a strong correlation between starch accumulation and shoot initiation. The accumulation started before any observable organized development and was heaviest in cells of loci which ultimately gave rise to organ primordia. Treatment of tissue cultures with gibberellin prevented starch accunmulation and organ formation.