Plant protecting and regulating compositions – Plant growth regulating compositions – Micro-organisms or from micro-organisms
Reexamination Certificate
2001-11-29
2004-02-10
Pryor, Alton (Department: 1616)
Plant protecting and regulating compositions
Plant growth regulating compositions
Micro-organisms or from micro-organisms
Reexamination Certificate
active
06689718
ABSTRACT:
FIELD OF THE INVENTION
The subject invention pertains to the field of agriculture, more particularly to the biocontrol of undesirable plant species.
BACKGROUND OF THE INVENTION
Tropical soda apple (
Solanum viarum
Dunal; TSA) is a prickly perennial weed species indigenous to South America. Introduced into Florida in 1988 it has since become one of the most serious invasive weeds in the southeastern United States (Mullahey, 1996). Tropical soda apple is designated a noxious weed under the Federal Noxious Weed Statutes. It proliferates rapidly by both sexual and asexual means. TSA is dispersed by cattle, birds, wild animals, and certain ranching and agricultural practices. In addition to being a highly competitive weed, TSA poses an additional threat as a reservoir for several economically important plant viruses (McGovern et al., 1994). TSA is currently managed by a combination of mowing and application of the chemical herbicide triclopyr (Remedy®) (Akanda et al., 1997), but alternative means of control are necessary and desirable.
SUMMARY OF THE INVENTION
All references cited herein are incorporated by reference in their entirety, to the extent not inconsistent with the explicit teachings set forth herein.
As an alternative to chemical herbicides, we searched for a suitable pathogen of tropical soda apple (TSA) for development as a bioherbicide and have discovered that Tobacco mild green mosaic virus (TMGMV) induces a lethal, systemic, hypersensitive response in TSA. TMGMV is a member of the tobamoviruses, which consist of mechanically transmitted, rod-shaped, RNA viruses that are strictly plant pathogens. The type species of Tobamovirus is Tobacco mosaic virus U1 (TMV U1), a widely distributed plant virus. Unlike TMGMV, TMV U1 and Tomato mosaic virus (ToMV, another Tobamovirus species), caused only mild, nonlethal mosaic or mottling of the TSA leaves. The atypical lethal effect of TMGMV on TSA was unexpected and is previously unknown. Also unknown was the feasibility to use TMGMV as a biocontrol for TSA.
Tropical soda apple serves as a host for TMV U1, ToMV, and TMGMV. In contrast to the mild, systemic mosaic symptoms caused by TMV U1 and ToMV, TMGMV causes rapid death of TSA. This death occurs due to a massive, systemic, hypersensitive plant response to infection by the virus. Both serological and molecular evidence confirm that TMGMV is responsible for the rapid and high rate of mortality on TSA. The age of TSA at the time of TMGMV inoculation does not affect the mortality rates, but the first expression of symptoms and first plant mortality are slightly delayed in older plants as compared to younger plants. Thus, the ability to control TSA by TMGMV is not limited by plant age. Temperature is usually not a limiting factor, although disease development will be slowed or prevented if the inoculated TSA plants are maintained continuously at 32° C. (or presumably at higher temperatures). However, under normal field conditions, a diurnal temperature fluctuation will occur and as our results indicate, TMGMV kills TSA plants under the diurnal cycle of 32/22° C. temperatures. To avoid possible adverse effects of high temperatures according to the subject invention, the TMGMV is preferably used in the field during the cooler months of spring and fall.
The host reaction of two
C. annuum
cultivars indicates that, as a precaution, TMGMV should not be used in the vicinity of pepper crops. However, it is safe to use the virus near tomato and eggplant crops.
Field trials from Hawthorne (north-central Florida) and Deseret Ranch (south-central Florida) sites confirm the excellent efficacy of TMGMV as a biological control agent for TSA. The high temperature-induced, attenuated disease symptoms, seen in plants incubated at 32° C., did not occur at either field site. Furthermore, the levels of TSA control obtained with TMGMV were comparable to the control levels obtained with chemical herbicides, but without the risks of chemical contamination.
Other advantages of TMGMV are first, the feasibility to produce abundant supplies of the virus by a simple, inexpensive method in susceptible tobacco; and second, the extremely small doses needed for high levels of TSA control. This virus-based bioherbicide system can be produced, developed, and registered more easily than fungal-based bioherbicides. Another important aspect of the TSA-TMGMV system is its highly novel mode of action, which is based on a systemic hypersensitive host response triggered by a gene of the virus.
Accordingly, it is an object of the present invention to provide a novel method of weed control.
It is a further object of the present invention to provide a method of weed control utilizing tobomoviruses.
It is a still further object of the present invention to provide a method of weed control utilizing TMGMV.
It is a still further object of the present invention to provide a method of controlling the tropical soda apple utilizing TMGMV.
Further objects and advantages of the present invention will become apparent by reference to the following detailed disclosure of the invention and appended photographs.
REFERENCES:
patent: 4162912 (1979-07-01), Charudattan
Pettersen, M. et al., Tobacco mild green mosaic tobamovirus strain U2 causes a lethal hypersensitive response in Salanum viarum Dual (tropical soda apple) Abstr. Meet. Weed Sci. Soc. AM 40;84, 2000.
Pettersen, M. Tobacco mild green mosalc virus (TMGMV) induces a lethal hypersensitive response in tropical soda apple (Solanum viarum Dunal), Phytopahtology, 91(6):S71-S72., 2001 (abstract).
Students of the Plant Pathology Dept, The Newsletter of the Plant Pathology Dept. at the University of Florida, 5(1), page 3 column 2, paragraph 1, 2001.
Students of the Plant Pathology Dept, The Newsletter of the Plant Pathology Dept. at the University of Florida, 5(2), page 3 column 2, paragraphs 2-3, 2001.
Session and Oral Presentations, Aps. Son. MSA Joint Meeting, Aug. 25-29, 2001.
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Dawson, W.O. 1999. Tobacco mosaic virus virulence and avirulence. Phil. Trans. R. Soc. Lond. B 354:643-651.
Duan, Y.P., Castañeda, A., Zhao, G., Erdos, G., Gabriel, D.W. 1999. Expression of a single, host specific, bacterial pathogenicity gene in plant cells elicits division, enlargement, and cell death. Molec. Plant-Microbe Interact. 12:556-560.
Erickson, F. L., Holzberg, S., Calderon-Urrea, A., Handley, V., Axtell, M., Corr, C., and Baker, B. 1999. The helicase domain of the TMV replicase proteins induces the N-mediated defense response in tobacco. Plant Journal 18, 67-75.
McGovern, R.J., Polston, J.E., and Mullahey, J.J. 1994.Solanum viarumDunal: weed reservoir of plant viruses in Florida. Int. J. Pest Manage. 40:270-273.
Mullahey J.J. 1996. Tropical soda apple (Solanum viarumDunal), a biological pollutant threatening Florida. Castanea 61:255-260.
Padgett, H. S. Watanabe, Y., and Beachy, R. N. 1997. Identification of the TMV replicase sequence that activates the N gene-mediated hypersensitive response. Mol. Plant-Microbe Interact. 10:709-715.
Purcifull, D.E. 1990. Ouchterlony double-diffusion tests in the presence of sodium dodecyl sulfate for detection of virion proteins and virus-induced inclusion proteins. pp. 179-196 in: R. Hampton, E. Ball, and S. De Boer, eds., Serological Methods for the Detecti
Charudattan Raghavan
Hiebert Ernest
Pettersen Matthew Scott
Pryor Alton
Saliwanchik Lloyd & Saliwanchik
University of Florida Research Foundation Inc.
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