Multicellular living organisms and unmodified parts thereof and – Plant – seedling – plant seed – or plant part – per se – Higher plant – seedling – plant seed – or plant part
Reexamination Certificate
2002-08-28
2004-11-23
Kruse, David H (Department: 1638)
Multicellular living organisms and unmodified parts thereof and
Plant, seedling, plant seed, or plant part, per se
Higher plant, seedling, plant seed, or plant part
C435S416000, C800S260000, C800S266000, C800S298000, C800S300000, C047S05810R
Reexamination Certificate
active
06822146
ABSTRACT:
FIELD OF INVENTION
This invention concerns sunflower plants and more particularly, sunflower seeds that have developed resistance to sulfonylurea herbicides through mutagenesis.
BACKGROUND OF THE INVENTION
Cultivated sunflower (
Helianthus annuus
L.) is a diploid species (2n=34) grown in many temperate, semi-dry regions of the world as a source of oil and confectionery seeds. Oil types of sunflowers contain 40 to 48 percent oil in the seed. Sunflower oil is valued as an edible oil, because of its high unsaturated fat level and light color. Sunflower oil is used for salads, cooking oil or for margarine. The protein content of sunflower meal prepared from seeds after oil extraction is useful as livestock feed. The seeds from both oil and confectionery varieties of cultivated sunflower are useful as bird food.
Only a relatively few herbicides have been found and developed for selective weed control in cultivated sunflower. These herbicides include alachlor, S-ethyl dipropylcarbamothioate (EPTC), ethalfluralin, trifluralin, pendimethalin, chloramben, imazamethabenz-methyl, sethoxydim and sulfentrazone. Additional weed control treatments are needed to provide a better spectrum of weed control and to reduce the development of weed resistance to herbicides.
Among the weeds insufficiently controlled by herbicides presently used in cultivated sunflower are members of the Orobanchaceae family. These weeds are obligate root holoparasites of a number of broadleaf plants, including sunflower. Particular
Orobanche
species afflicting sunflower include
Orobanche aegyptiaca
Pers.,
O. ramosa
L.,
O. minor
Sm.,
O. cumana
Wallr. and
O. cernua
Loefl.
O. cumana
Wallr. and
O. cernua
Loefl. (alternative names for the same species) is a severe pest in sunflower in eastern Europe and has been spreading through southern Europe.
Orobanche
presents a worldwide risk, and some species such as
O. minor
have appeared as exotics in the United States.
Orobanche
species are very difficult to eliminate, because, except for their flower parts, they live in the soil, and their seeds are minute, prolifically produced, easily dispersed and very long-lived. Thus, herbicides presently used in sunflower generally provide inadequate control.
Since the discovery of sulfonylurea herbicides over twenty years ago, over two dozen sulfonylureas have been commercially developed for selective weed control in a wide variety of crops (
The Pesticide Manual, Eleventh Edition
, C. D. S. Tomlin, ed., British Crop Protection Council, Surrey, U.K., 1997). Sulfonylurea herbicides have as an essential molecular structural feature a sulfonylurea moiety (—S(O)
2
NHC(O)NH(R)—). The sulfonyl end of the moiety is connected either directly or by way of an oxygen atom or an optionally substituted amino or methylene group to a cyclic or acyclic group. At the opposite end of the sulfonylurea bridge, the amino group, which may have a substituent such as methyl (R being CH
3
) instead of hydrogen, is connected to a heterocyclic group, typically a symmetric pyrimidine or triazine ring, having one or two substituents such as methyl, ethyl, methoxy, ethoxy, methylamino, dimethylamino, ethylamino and the halogens. As the mode of action of sulfonylurea herbicides is inhibition of the enzyme acetolactate synthase (ALS) found in plants but not animals, sulfonylurea herbicides provide a valued combination of excellent efficacy against weeds and very low toxicity to animals.
While sulfonylureas have been developed for selective weed control in a variety of crops, ordinary varieties of cultivated sunflower are generally insufficiently tolerant for sulfonylureas to be useful for selective weed control in sunflower crops. However, preemergence application of a low dose (2 to 6 g/ha) of chlorsulfuron has been reported to result in 75-85% control of
O. cernua
with sunflower tolerance (L. García-Torres et al.,
Weed Research
1994, 34, 395-402). Although sulfonylurea herbicides have thus been shown to have effect on
Orobanche
species, the sensitivity of ordinary varieties of sunflowers to sulfonylureas prevents use of higher application rates to give better control of
Orobanche.
Greater application rates of sulfonylurea herbicides could be used to control
Orobanche
as well as other weed species if varieties of sunflower more resistant to sulfonylureas could be developed. To be easily incorporated in breeding programs combining desirable traits, the trait for sulfonylurea tolerance should be highly heritable (i.e. dominant or semi-dominant). Induced mutagenesis has been used to produce sulfonylurea resistance in soybeans, as discussed in U.S. Pat. No. 5,084,082, but this approach has not been reported for sunflower, which has dissimilar seed morphology compared to soybean. Furthermore because 99% of induced mutations are recessive (W. Gottschalk & G. Wolff
Induced Mutations in Plant Breeding
, Springer-Verlag, N.Y., 1983, particularly p. 12), dominant mutations are extremely rare. To find dominant herbicide resistance mutations typically requires screening many thousands of mutagenized seeds.
Accordingly there is a need to be able to selectively control
Orobanche
and other weeds using sulfonylurea herbicides. Applicants have conducted an extensive research program to find dominant or semi-dominant mutant traits providing sulfonylurea resistance in cultivated sunflower.
SUMMARY OF THE INVENTION
This invention relates to a method for producing a sunflower line containing a highly heritable trait conferring tolerance to sulfonylurea herbicides, wherein the method comprises: (a) treating sunflower seeds with a mutagenic agent; (b) growing the treated seeds into mature plants to produce second-generation seeds; (c) harvesting the second-generation seeds; (d) germinating the second-generation seeds in the presence of an selectably effective amount of a sulfonylurea herbicide to select for survival only germinated seeds containing a trait conferring tolerance to the sulfonylurea herbicide; and (e) growing a surviving germinated seed into a mature plant to produce through self-pollination seeds of the sunflower line containing the heritable trait.
This invention also relates to a sunflower seed containing a highly heritable trait conferring tolerance to sulfonylurea herbicides, wherein the trait is obtained through mutagenesis. Another embodiment of this invention is a sulfonylurea-tolerant sunflower plant, a part thereof such as pollen or an ovule, or a tissue culture of regenerable cells therefrom, grown from the aforementioned sulfonylurea-tolerant seed. The aforementioned seed and plants may additionally contain other desirable traits, such as resistance to
Orobanche
parasitism.
Another aspect of the invention is a method for producing inbred sunflower seed having tolerance to sulfonylurea herbicides comprising crossing a first parent sunflower with a second parent sunflower plant and harvesting the resultant inbred seed, wherein the first and second parent sunflower plants have a highly heritable trait conferring tolerance to sulfonylurea herbicides, wherein the trait is obtained through mutagenesis. Related embodiments include an inbred sunflower seed produced by this method and an inbred sunflower plant, or a part thereof such as a seed, produced by growing the inbred seed. Still another aspect of the invention is a method for producing hybrid sunflower seed having tolerance to sulfonylurea herbicides comprising crossing a first parent sunflower with a second parent sunflower plant and harvesting the resultant hybrid sunflower seed, wherein the first or second parent sunflower plant has a highly heritable trait conferring tolerance to sulfonylurea herbicides, wherein the trait is obtained through mutagenesis. Related embodiments include a hybrid sunflower seed produced by this method and a hybrid sunflower plant, or a part thereof such as a seed, produced by growing the hybrid seed.
A further aspect of the invention pertains to a method for controlling undesired vegetation in a crop of the aforementioned sulfonylurea-toler
Gabard Jerome M.
Huby Jean Pierre
E. I. du Pont de Nemours and Company
Kruse David H
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