(1) Field of the Invention
The present invention relates to a method for the production of plants of the Class Monocotyledonae (“monocots”) on a large scale, and more particularly to a method for the production of cloned monocot plants with the potential for the production of transgenic monocot plants, and to the monocot plants produced by the method.
(2) Description of the Related Art
Induction of regenerable tissue cultures from monocot species is conventionally attempted from immature embryos or immature inflorescences. Both approaches have been shown to work on Typha glauca, T. angustifolia and T. latifolia (Rogers, S. D. et al., Plant Cell Reports, 18:71-75 (1998). No report of tissue culturing of the fourth North American species, T. dominguensis, has been found.
Tissue culture of only two Juncus species has been reported, (Sarma, K. S. et al., Plant Cell Rep., 17:656-660 (1998), Sarma, K. S. et al., Aquatic Botany 68: 239-247 (2000), and no reports of regenerable tissue cultures have been found for species of the grass, Erianthos giganteus, sedges of the genera Cyperus and Carex, and bulrushes of the genus Scirpus. 
Plant regeneration from cultured cells of the great majority of monocot (mostly graminaceous) species that have been reported so far, is achieved from callus initiated on high concentrations of a strong auxin, such as 2,4-dichlorophenoxyacetic acid (2,4-D) (Conger, B. V. et al., pp. 59-68 in Current Issues in Plant Molecular and Cellular Biology, (1995)).
One monocot, Arundo donax L., or Giant Reed, of the Order Poales and the Family Poaceae (Gramineae), is one of the largest grasses in the world, and is an attractive, robust, perennial reed. Tucker, G. C., J. Arnold Arb., 71:145-177 (1990). The very strong, somewhat woody, clustering culms, which grow from horizontal knotty rootstocks, are known to grow to a height of 8-10 meters and to have a diameter of from 1 to 4 cm. Bailey, L. H., Manual of cultivated plants: Most commonly grown in the continental United States and Canada, Rev. Ed., MacMillan, New York, (1954); and Mabberley, D. J., The plant-book: a portable dictionary of the vascular plants, 2nd Rev., Cambridge Univ. Press, Oxford (1997). It is one of the largest of the herbaveous grasses and has fleshly, creeping rootstocks that form compact masses from which arise tough fibrous roots that penetrate deeply into the soil. The culms commonly branch during the second year of growth and are hollow with walls of 2 to 7 mm thick.
The plant is known by a variety of common names, including carrizo, bamboo reed, Danubian reed, donax cane, Italian reed, Provence cane and Spanish reed. A. donax probably originated from the freshwaters of the warm regions of eastern Asia. It has been in cultivation in Asia, North Africa, and the Middle East for thousands of years and also in North and South America, Australia and South Africa, during the past century. Further information on the culture of A. donax can be found, for example, in Bell, G. P. Ecology and management of Arundo donax, and approaches to riparian habitat restoration in Southern California, in Plant Invasions: Studies From North America and Europe, Brock, J. H. et al., Eds. pp.103-113, Backhuys Publishers, Leiden (1997); Perdue, R. E., Econ. Bot., 12:368-404 (1958); Rossa, B. et al., Bot. Acta, 111:216-221 (1998); Roys, R., Ethnobotany of the Maya: The Department of Middle American Research, M.A.R. Series Pub. 2, Tulane U., New Orleans (1931); Zahran, M. A. et al., The vegetation of Egypt, Chapman & Hall, London (1992); and Zohary, M., Plant Life of Palestine, Ronald Press, New York (1962).
Plants from the Class Monocotyledonae, such as A. donax, are often multipurpose plants. Giant reed, for example, has been used for 5,000 years for pipe instruments and is the source for reeds for clarinets and organ pipes. Even with today's modern technology, most of the reeds for woodwind musical instruments are still made from A. donax culms.
Giant reed is also used for erosion control and has great potential for use as an energy crop. Szabo, P., et al., J. Anal. Appl. Pyrolysis, 36:179-190 (1996). The culms are also used for fishing rods, walking sticks, mats and lattices in the construction of adobe huts. Giant reed is also a source of industrial cellulose for paper and rayon making, and for the production of other polysaccharides. Neto, C. P. et al., Ind. Crops & Prods., 6:51-58 (1997). It has even been considered as a source of pulp for the making of paper. Perdue, R., Arundo donax: Source of Musical Reeds and Industrial Cellulose, www.wuarchive.wustl.edu/doc/misc/org/doublereeds/general/cane.html.
Giant reed grows very rapidly. When conditions are favorable, growth at a rate of 0.3 to 0.7 meter per week for several weeks is not unusual. Young culms typically grow to their full diameter within the initial growing season, but their walls increase in thickness thereafter.
Outside its native range and the Mediterranean, however, the plant is sterile; it flowers, but does not produce viable seed. It reproduces vegetatively efficiently from fragments of stems and rhizomes. Boose, A. B. etal., Weed Res., 39:117-127 (1999). Traditional horticultural propagation of giant reed is by division of rhizomes. However, the propagation of giant reed by either rhizome division, or by traditional seed culture require a significant amount of time and effort between the initiation of division, or planting, and the successful establishment of a growing plant. Moreover, conventional methods of propagation provide limited opportunity for genetic manipulation, and, in the case of seeds, do not permit genetic control of the resulting progeny. Such conventional techniques also require large areas for the production of a sufficient number of plants to be useful in programs for the production of fuel or biomass, or for use in bioremediation programs.
Giant reed is only one of the monocots that exhibits such multiple uses. Whether used as ornamentals, sources of energy, or as useful vehicles to carry out industrial processes, such grass-like plants are important.
Accordingly, it would be useful to be able to provide a method by which plants of the Class Monocotyledonae, and in particular, plants such as those of Juncus spp., Scirpus spp., Cyperus spp., Carex spp., Erianthus spp., and Typha spp, could be propagated even in areas in which plants of these genera are sterile and in a manner that would require shorter time, less effort and less area than conventional methods. In particular, it would be useful if a method could be provided that permitted better genetic manipulation and control of the plants. Moreover, it would also be useful if the method was independent of seasons and was sustainable at a high rate of propagation.