Multicellular living organisms and unmodified parts thereof and – Method of introducing a polynucleotide molecule into or... – The polynucleotide confers pathogen or pest resistance
Reexamination Certificate
1996-12-04
2002-06-18
Nelson, Amy J. (Department: 1638)
Multicellular living organisms and unmodified parts thereof and
Method of introducing a polynucleotide molecule into or...
The polynucleotide confers pathogen or pest resistance
C800S284000, C800S290000
Reexamination Certificate
active
06407313
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of plant biology. More particularly, the present invention is directed to compositions and methods for use in regulation of plant growth.
This invention was made with Government support under Grant No. DCB-90-16756 and INB-94-06974, awarded by the National Science Foundation, and Grant No. 90-00070, awarded by the United States Department of Agriculture. The Government has certain rights in this invention.
2. Description of the Related Art
Present strategies for controlling plant developmental and physiological functions rely on traditional genetic approaches, or on biotechnological approaches that lack a fully refined conceptual foundation. In terms of manipulation of plant resource allocation, the only approach currently available involves the use of genetic breeding for a desired trait; this is recognized as a slow and complex process. Furthermore, current strategies fail to provide any understanding of the underlying molecular events that are involved in the prioritization of resource allocation to the various regions of the plant body.
Partitioning of assimilates in plants is an important and highly regulated process [Wardlaw I. F. (1990) The control of carbon partitioning in plants.
New Phytologist
116, 341-381]. It involves regulation of photosynthesis, intracellular and intercellular transport of metabolites, phloem loading and unloading, storage and other interrelated biochemical processes. Partition of assimilates is closely related to the regulation of growth and development, in as much as growth of different plant parts and organs often requires the import of assimilates from elsewhere in the plant. The relationship between root and shoot biomass is an excellent example of regulation of partition of assimilates. Root-to-shoot ratios vary from plant species-to-species, and are influenced by the environment [Geiger D. R. & Servaites J. S. (1991) Carbon allocation and response to stress. In
Response of plants to multiple stresses
(eds. H. A. Mooney, W. E. Winner & E. J. Pell ) pp. 103-127. Academic Press, New York; Mooney H. A. & Winner W. E. (1991) Partitioning response of plants to stress. In
Response of plants to multiple stresses
(eds. H. A. Mooney, W. E. Winner & E. J. Pell) pp. 129-141. Academic Press, New York]. Furthermore, this ratio is responsive to water stress and nutrient deficiencies, and it can be manipulated by exogenous hormonal treatments and light quality [Britz S. J. (1990) Photoregulation of root: shoot ratio in soybean seedlings.
Photochemistry and Photobiology
52, 151-159; Incoll L. D., Ray J. P. & Jewer P. C. (1990) Do cytokinins act as root to shoot signals? In
Importance of root to shoot communication in the responses to environmental stress
, Monograph 21 (eds. W. J. Davies & B. Jeffcoat) pp. 185-199. British Society for Plant Growth Regulation, Bristol; Davies W. J. & Zhang J. (1991) Root signals and the regulation of growth and development of plants in drying soil.
Annual Review of Plant Physiology and Plant Molecular Biology
42, 55-76; Tolley-Henry L. & Raper C. D. (1991) Soluble carbohydrate allocation to roots, photosynthetic rate of leaves and nitrate assimilation as affected by nitrogen stress and irradiance.
Botanical Gazette
152, 23-33].
The finding [Lucas W. J., Olesinski A., Hull R. J., Haudenshield J. S., Deom C. M., Beachy R. N. & Wolf S. (1993) Influence of the tobacco mosaic virus 30-kDa movement protein on carbon metabolism and photosynthate partitioning in transgenic tobacco plants.
Planta
190, 88-96] that a significant reduction in biomass partitioning to roots occurs in transgenic tobacco plants that express the tobacco mosaic virus movement protein (TMV-MP) has raised questions as to the possible effects of this protein on the integrated physiology of tobacco plants. It is now well established that the TMV-MP interacts with plasmodesmata to potentiate virus trafficking between cells [Deom C. M., Oliver M. J. & Beachy R. N. (1987) The 30-kDa gene product of tobacco mosaic virus potentiates virus movement.
Science
237, 389-394; Wolf S., Deom C. M., Beachy R. N. & Lucas W. J. (1989) Movement protein of tobacco mosaic virus modifies plasmodesmatal size exclusion limit.
Science
246, 377-379; Ding B., Haudenshield J. S., Hull R. J., Wolf S., Beachy. R. N. & Lucas W. J. (1992) Secondary plasmodesmata are specific sites of localization of the tobacco mosaic virus movement protein in transgenic tobacco plants.
Plant Cell
4, 915-928; Waigmann E., Lucas W. J., Citovsky V. & Zambryski P. (1994) Direct functional assay for tobacco mosaic virus cell-to-cell movement protein and identification of a domain involved in increasing plasmodesmal permeability.
Proc. Natl. Acad. Sci. USA
91, 1433-1437]. In transgenic tobacco plants expressing the TMV-MP, the size exclusion limit (SEL) of plasmodesmata connecting the mesophyll and bundle sheath cells was found to be increased from 800 Da to greater than 9.4 kDa [Wolf et al. 1989, supra; Deom C. M., Wolf S., Holt C. A., Lucas W. J. & Beachy R. N. (1991) Altered function of the tobacco mosaic virus movement protein in a hypersensitive host.
Virology
180, 251-256; Ding et al. 1992, supra]. This observation raised the possibility that dilated plasmodesmata, within such tissues, may enhance symplasmic carbohydrate transport between cells [Lucas W. J. & Wolf S. (1990) Plasmodesmatal function probed using transgenic tobacco plants. In
Recent advances in Phloem transport and assimilate compartmentation
(eds. J. L. Bonnemain, J. Dainty, S. Delrot & W. J. Lucas) pp. 106-115. Ouest Editions, Nantes Cedex; Lucas et al. 1993, supra]. However, contrary to this expectation, these transgenic plants exhibited a decrease in translocation of assimilates, from source leaves, during the day [Lucas et al. 1993, supra].
Also, in such transgenic plants expressing the TMV-MP, root-to-shoot ratios were significantly smaller, reflecting reduced carbon allocation and translocation to the roots [Lucas et al. 1993, supra]. It is thus of great interest that the TMV-MP affects not only the dilation of plasmodesmata and virus trafficking, but also carbohydrate metabolism and resource allocation, as reflected by changes in root-to-shoot ratios.
Similar considerations are involved in understanding the distribution of other plant products, such as sucrose. Sucrose synthesis occurs within the cytosol of tobacco mesophyll cells, but the pathway followed by sucrose during its movement from the site of synthesis to the cells of the phloem remains equivocal. The prevailing view is that solute movement between mesophyll cells occurs via a symplasmic route through plasmodesmata [Giaquinta, R. T. (1983) Phloem loading of sucrose.
Ann. Rev. Plant PhysioL
34, 347-387; Tucker, J. E., Mauzerall, D., Tucker, E. B. (1989) Symplastic transport of carbxyfluorescin in staminal hairs of
Setcreasea purpurea
is diffusive and includes loss to the vacuole.
Plant Physiol
. 90, 1143-1147; Robards, A. W., Lucas, W. J. (1990) Plasmodesmata.
Annu. Rev. Plant PhysioL Plant Mol. Biol.
41, 369-419]. In many species, however, the actual process involved in loading into the sieve element-companion cell complex may involve an apoplasmic step [van Bel, A. J. E. (1992) Pathway and mechanisms of phloem loading. In:
Carbon partitioning within and between organisms
(eds. Pollock, C. J., Farrar, J. F., Gordon, A. J.) pp. 53-70. BIOS Scientific Publishers, Ltd., Oxford]. Furthermore, it remains to be elucidated whether the loading process constitutes the rate-determining step, or major control site, in the export of recently fixed photosynthate.
Experimental control over plasmodesmal SEL has recently been achieved using expression of viral movement proteins (MPs) in transgenic plants. In transgenic tobacco expressing the MP of tobacco mosaic virus (TMV-MP), this movement protein becomes localized to mesophyll plas
Nelson Amy J.
O'Banion John P.
The Regents of the University of California
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