CA2509439A1 - Fusarium resistant tetraploid wheat - Google Patents

Abstract

The invention provides Fusarium resistant tetraploid wheat. The invention also provides seeds, plant parts and progeny of Fusarium resistant tetraploid wheat

Description

Attorney Docket No.: 255.00080101 FUSARII>M RESISTANT TETRAPLOID WHEAT
This application claims the benefit of U.S. Provisional Application Serial No. 60/577.854, filed 8 June 2004, which is incorporated herein by reference in as entirety.
STATEMENT OF GOVERNMENT RIGHTS
This invention was made with government support under a grant from the United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Grant No. 59-0790-9-033. The U.S. Government has certain rights in this invention.
BACKGROUND OF THE INVENTION
Dun~rn wheat (the tetraploid wheat Triticum te~r-gidum L. var. durmn, synonym T durum) is one of the most important cereal crops in the world. Also known as "hard" wheat or macaroni wheat, it is cultivated in semiarid regions of the world such as North Africa, Mediterranean Europe, the North American Great Plains and the Middle East. Its kernel size, hardness and golden amber color make it most suitable for manufacturing a unique and diverse range of food products. Pasta and couscous are the most common paste products made from durum wheat.
Durum wheat also can be used for making bread, however, bread wheat (the hexaploid wheat T. aeStivum) is the main source of flour for making bread.
Generally bread wheat is not used to manufacture pasta or couscous.
Wheat belongs to the genus Triticum, all members of which contain a multiple of the basic haploid set of seven chromosomes (x = 7). The wheats form an allpolyploid series with diploid (2n = 2x =14), tetraploid (2n = 4x=28), and hexaploid (2n = 6x =42) species. Within each species, chromosomes pair in a diploid-like fashion, and the mode of inheritance is disornic.
Cytogenetic, biochemical, morphological and genetic analyses have been used to assess the evolutionary development of the cultivated tetraploid and hexaploid wheat. The designated A-genome is derived from the diploid T.

.,:
monococcurn L. (synonyms T. boeoticu m and T. urartu). T_ monococcurn was long considered the A-genome donor. At the wild tetraploid level. T.
dicocoides (AABB) may have the A-genome from T. monococcum and the B-genome of T.
.speltoirles (Tausch) Gren. Ex Richter. synonym Aegilops speltoides. Common S bread wheat, the hexaploid T. aestivum (AABBDD) has the A- and B-genomes of a tetraploid T. tur-gidum and the D-genome derived from T. taushii (Coss.) Schmal., synonym Aegilops sgarrosa. The two species T. turgidum L. var.
dicoccoides and Aegilops .rgaurrosa are considered the nearest wild progenitors of common bread wheat. T. dicoccoides is the only wild member of the wheat group fully interfertile with cultivated T. turgidum L var. durum.
The tetraploid emmer wheats T. dicoccunT shrank, T_ dicoceoides, and T.
turgidum L var. durum also can be crossed directly with hexaploid wheats. The F, generation may exhibit a high degree of sterility, but seed set can be obtained.
Fusarium head blight (FHB) is caused by the fungus Fusarium, typically 1 S F. graminearurn Schwabe (telomorph Gibberella zea (Schwein.) Petch) but other causal agents can include F. culmorum and F. avenaceum. Fusarium head blight is a serious threat to durum wheat. Since 1993, it is estimated that Fusarium head blight has cost over $3 billion in direct and indirect losses in North Dakota (Sayler, Scab on rampage: where do we go from here? Prairie Grains, November/December, issue IO ppl4, 19-21, 3S and 39 (1997)).
Fusarium head blight not only reduces yield but also reduces the quality of the end products of durum wheat (Dexter et al., Cereal Chem., 74:519 ( 1997)). The fungus is also associated with mycotoxins, particularly trichothecene deoxynivalenol (DON vomitoxin), that are hazardous to humans and other 2S animals.
There is a continuous decline in harvested durum acreage and production in North Dakota because of Fusarium head blight. The harvested acreage in North Dakota in 2001 was 2.25 million acres. This acreage is 22070 less than the year 2000 (State of North Dakota, Agriculture Statistics). In 2001 North Dakota produced 60.75 million bushels of durum wheat, which was a 22070 decrease in production as compared to production in the year 2000 (National Agriculture Statistics, 2001 ). The decline in harvested acreage and durum production in North Dakota is disastrous to the farm economy and has direct impact on the national pasta industry. In addition, the international export market is also

2 greatly affected since North Dakota on average produces 7S9o of the durum in the United States.
Fungicides can be used to improve yield and other agronomic traits but the level of improvement is below the margin of the economic return (McMullen, Evaluation of fungicides for suppression of Fusarium head blight.
in Current research on Fusarium head blight of small grains, November ( 1997) NDSU research publication, Fargo, North Dakota ( 1997)). Although fungicides may reduce Fusarium head blight, the use of genetic resistance is the most environmentally safe and economical way to control the disease. Durum wheat with appropriate combinations of resistant genes could effectively control the disease. Accordingly, what is needed is the development of wheat, particularly durum wheat, that is genetically resistant to Fccsarium.
SUMMARY OF THE INVENTION
'The invention provides Fusarium resistant tetraploid wheat as well as methods for making and using such wheat. A preferred embodiment of the method of producing Fusariunn resistant tetraploid wheat includes crossing Fusarium resistant hexaploid wheat with a tetraploid wheat to produce F, progeny, backcrossing the F, progeny with a tetraploid wheat to produce backcrossed F, (BC,F,) progeny, and selfing the backcrossed F, (BC,F,) progeny to produce backerossed progeny (BC,FZ) that include the Fecsarium resistant tetraploid wheat.
Seeds and other plant parts of Fusarium resistant tetraploid wheat, such as a leaf, stem, root, embryo, meristematic tissue, callus tissue, germplasm, gametophyte, saprophyte, pollen or microspore, are also provided by the invention. Progeny of Fusarium resistant tetraploid wheat plants, including progeny of crosses and backcrosses utilizing Fusarium resistant tetraploid wheat, are also included in the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a gray scale for determining Fusarium head blight (FHB) disease severity (% disease severity is indicated on the x-axis) (Stack and McMullen, A visual scale to estimate severity of Fusarium head blight in wheat.
No. Dak. St. Univ. Bull. P-1095 (1995)).

3 Figure 2 is a gray scale version of color photographs showing FHB
severity (~e disease severity is indicated on the x-axis) (Stack and McMullen, A
visual scale to estimate severity of Fusarium head blight in wheat. No. Dak.
St.
Univ. Bull. P-1095 (1995)).
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODTMENTS
The present invention is based on the discovery that resistance to Fusarium head blight (FHBj (also referred to herein as "Fusarium resistance"
or "FHB resistance") can be transferred from known Fu.sariurn resistant hexaploid wheat to tetraploid wheat through use of the method of the invention.
Accordingly, the invention also provides Fusarirrm resistant tetraploid wheat, and products thereof, that will help to provide good quality wheat for the future.
'The Fatsarium resistant wheat produced according to the method is produced through use of basic plant breeding and is therefore not a genetically modified organism.
The term "wheat" as used herein includes generally any plant of the wheat genus (Triticum) including wheat species, varieties, subvarieties, hybrids, cultivars, lines, strains and the )ike.
Hexaploid wheat The method for producing a Fusariurn resistant tetraploid wheat involves the transfer of Fursarium resistance from a hexaploid Fusarium resistant wheat to a tetraploid wheat. Many types of Fusurium resistant hexaploid wheat are known. Examples of Fusarium resistant hexaploid wheat varieties include, but are not limited to, Sumai 3 wheat, Ning 7840 wheat, Frontana wheat, Nobeokabouza wheat, 2375 wheat, Ernie wheat, Freedom wheat and Wnagshuibai wheat (Rudd et al., Crop Sci., 41.620 (2001)). Many of these types of Fusarium resistant hexaploid wheat have molecular markers that are associated with the Fusarium resistance, such as Xgwm2, Qfhs.ndsu-3BS and Xgwm533 (Rudd et al., Crop Sci_, 41:620 (2001 ) and Anderson et al., Theor.
Apl. Genet., 102:1161 (2001)). These types of Fusarium resistant hexaploid wheat, and others, may be used within the method of the invention to produce Fusarium resistant tetraploid wheat.

4 The Fc~sariunn resistant hexaploid wheat. Samai 3, is probably the most widely used wheat from which Fusarium resistance is obtained in the world. It has been used in Chinese breeding programs for at least 20 years (Liu, Recent advances in research on wheat scab in China. p. 174-181, in Wheat for more tropical environments. CIMMYT (Centro Internacional de Mejoramiento de Maiz y Trigo), Mexico, D.F. Mexico (1984)) and since introduction into the LISA, it has been used by winter and spring wheat breeders (Wilcoxson, Historical review of scab research, p. 1-5, in Proc. (1s') Regional Scab Forum, Moorhead, MN. Publ. Minn. Wheat Res. & Prom Council, Red Lake Falls, MN
(1993)). The FHB resistance in Sumai 3 is heritable, stable and consistent across environments_ The Fusarium resistant hexaploid spring wheat, Wnagshuibai, has also been used by wheat breeders in the USA, but has not been as widely used as Sumai 3. The FHB resistance in Wnagshuibai is also heritable, stable and l5 consistent across environments.
While Sumai 3 has been successfully used by hexaploid wheat breeders as a source of Fcrsarimn resistance. tetraploid durum wheat breeders have had no success in using it. This lack of success initially led breeders to believe that the resistance genes from Sumai 3 might be on the D-genome of hexaploid wheat and would therefore not recombine with tetraploid durum wheat where the D-genome is absent (the durum genome is AABB). However, the resistance genes from Sumai 3 have been mapped on the A-genome and the B-genome (Kolb et al., Crop Sci., 41:61 1 (2001 )). It is now believed that the genetic background of the elite durum germplasm may be suppressing the Sumai 3 resistance.
Accordingly, it was surprising when resistance from hexaploid Sumai 3 wheat and hexaploid Wangshuibai wheat was successfully transferred to tetraploid elite North Dakota durum wheat germplasm using the method of the invention.
Fu.sarium resistance Fusarium or FHB "resistance" refers to the ability of wheat to resist infection by Fusarium. There are a number of ways to measure resistance to FHB, which include measuring resistance to initial infection, resistance to spreading (Type II resistance), resistance to kernel infection, tolerance and toxin accumulation/degradation. Preferably, FHB resistance is evaluated using an

5 assay for "Type ll" resistance, where an infection is introduced into the middle of a stalk and the pant iS examined for spreading up or down the stalk. In a resistant plant, the infection will remain localized. perhaps infecting only one floweret or spikelet. >\-lost breeding programs target "Type II" resistance, i.e., resistance to spread of infection within the spike of a plant.
FHB resistance can be evaluated, for example, by examining the plant for disease after exposure to a Fusarium inoculum. Wheat can be planted and inoculated with Fu.sarium according to methods described herein and known in the art (e_g., Stack. Can. J. Plant Path., 1 I :137 ( 1989)). The wheat is then inspected to determine the level (e.g_, spreading) of Fusarium infection (disease severity) produced on the wheat_ A visual scale, as shown in Figure I and Figure 2, and as described in the an (e.g., Stack and McMullen, A visual scale to estimate severity of Fusarirrm head blight in wheat. No. Dak. St. Univ. Bull.
P-1095 ( 1995)) and in Example I below, is commonly used to assess resistance to 1.5 Fuscrrium. Frrsarium resistance can be tested under a variety of conditions. such as in a nursery setting and/or in a field setting.
Fusariur~~ resistance and disease severity are. of course, inversely related.
A high "% disease severity" value indicates that a wheat exhibits low resistance to Fusarirrrn while a low "% disease severity" value indicates that a wheat exhibits high resistance to Fusarium infection.
Hexaploid wheat is generally resistant to Fc~sarir~rn. Disease severity typically exhibited by hexaploid wheat ranges from 7% to 20%. Disease severity typically observed in non-Fusarium resistant tetraploid wheat ranges from 35% to 100%.
Preferably the level of disease severity of the Fusarium resistant tetraploid wheat of the invention is less than 32%, more preferably the level of disease severity of the Fusarium resistant tetraploid wheat is less than 20%, most preferably the level of disease severity of the Fusarium resistant tetrapIoid wheat is less than 10%. Preferably the level of disease severity of the Fusarium resistant tetraploid wheat is between 7% and 30%. More preferably the level of disease severity of the Fusarium resistant tetraploid wheat is between 7% and 20%. Most preferably the level of disease severity of the Fusarium resistant tetraploid wheat is between 7% and 10%.

6 Preferably a progeny tctraploid wheat to which Fusarium resistance is transferred through crossing with a Frrsarirrm resistant hexaploid wheat exhibits greater Fr~sarir.rm resistance than the parent tetraploid wheat.
The presence or level of Fcrsarium resistance can also be assessed through use of molecular markers that are linked to Fusarium resistance. For example, the rnicrosatellite locus Xgwm2 is tightly linked to Fr~sarirrm resistance (Otto et al., Plant Molecular Biology, 48:625 (2002)). Other examples of molecular markers that are associated with Fusarium resistance include a major quantitative trait loci that is designated Qfhs.ndsu-3BS, and a simple sequence repeat marker that is designated Xgwm533. Accordingly, wheat can be additionally assessed for Fusariurn resistance based on the presence of a molecular marker within the screened wheat. Additional markers that are associated with F~rrsariurn resistance can also be used to screen wheat for Fu.rarirrm resistance.
IS
Tetraploid w~l~eat Fusariunr resistance is transferred according to the invention from Fuscrr-ium resistant hexaploid wheat to tetraploid wheat. Tetraploid wheat includes, but is not limited to, T. dicoccum shrank, T. dicoccoides, and T.
turgidrrrn L var. durrrrn (durum wheat) and T. turgiclum polonicum (Kamut).
Preferably, the tetraploid wheat is a durum wheat. Examples of durum wheat varieties include Belzer, Ben, Dilse, Lebsock, Maier, Mountrail, Munich, Pierce, Plaza, Sceptre, Medora, D88096, D88816, D88090 and D88690. Preferably the tetraploid wheat to which Fusarium resistance is transferred is durum wheat.
Some durum wheat already exhibit a reduced level of Fusarium resistance. For example, the newly released cultivars: Lebsock (Elias et al., Crop Sci., 41:2007 ( 1999)), Plaza (Elias et al., Crop Sci., 41:2008 ( 1999)), Maier (Elias and Miller, Crop Sci., 40:1498 ( 1998)), Belzer (Elias et al., Crop Sci., 39:881 (1997)) and Ben (Elias and Miller, Crop Sci., 38:895 (1996)) have Less disease severity and deoxynivalenol (DON) levels than the older cultivars, Renville (Cantrell et al., Crop Sci., 29: I 329 ( I988)) and Monroe (Cantrell et al., Crop Sci., 26:200 ( 1985)). However, the level of resistance in these cultivars is still much lower than that found in hexaploid wheat germplasm. Observed disease seventies were within a range of 30% to 60%. It has been reported that

7 the durum Langdon diroccoide,s 3A substitution line (LDN(DIC-3A)] was less susceptible to FHB, 12.5'~o to 29.9c1c, than all the other substitution lines (Stack et al., Crop Sci., 42:637 (2002)). In comparison with the resistance of Sumai 3, LDN(Dl('.-3A) is characterized as moderately resistant, with a resistance of 19.8%. A microsateIlite locus, Xgmrn2, is tightly linked to this resistance (Otto et al., Plant Molecular Biology, 48:625 (2002)) and is being used in the durum breeding program at North Dakota State University (NDSU).
Plant breeding The method for producing Fusarirrm resistant tetraploid wheat includes crossing hexaploid Fusarium resistant wheat with tetraploid wheat to produce F, progeny, backcrossing the F, progeny with tetraploid wheat to produce a backcrossed F, (BC,Fi) progeny, and selfing the backcrossed F, progeny to produce backerossed progeny (BC,F~) that include members that are resistant to Fusarir.~m.
A single cross is a cross between two parents, for example between Sumai 3 (hexaploid) and Sceptre (tetraploid) which is labeled as Sumai 3/Sceptre. Making crosses requires emasculating the female flower and later pollinating it with pollen from the male flower_ Forceps are used for emasculation to remove the anthers from the female flower (female parent). The emasculated female l7ower is covered with glassine bags to avoid out-crossing.
Four to five days later when the flower is mature enough to be receptive, pollen is transferred from the male flower. 'Thirty days later hybrid seed is harvested and planted to produce F, progenies.
A "backcross," as that term is used herein, is a cross between (a) an F, progeny and (b) one of its parents or a variety with one or more similar features of a parent (the latter being sometimes known as a "top cross"). In the present method, the purpose of the backcross is to reconstitute the tetraploid background.
For example, after a hexaploid wheat (e.g., Sumai 3) is crossed with a tetraploid wheat (e.g., Sceptre), F, progeny can be crossed to another tetraploid wheat as a backcross. Sumai 3 can, for example. be crossed to Sceptre, and the resulting F, (Sumai 3/Sceptre) can be crossed to a tetraploid line D88816. This backcross is labeled as Sumai 3/Sceptre// D88816, with D88816 being used to reconstitute the tetraploid background.

8 Advantageously. Fccsarium resistant tetraploid wheat (for example, the experimental durum lines described in Example I) can be crossed with the germplasm of any tetraploid wheat of interest to produce an FHB resistant plant with additional desired traits. 'these traits exhibited by the plant can be observable in the plant's phenotype and/or genotype. The progeny of such crosses may exhibit traits such as improved yield, pasta quality and/or robustness. By crossing Fursurium resistant tetraploid Lines with other, agronomically acceptable lines, germplasrn can be developed that is both agronomically acceptable and disease resistant. The present invention thus encompasses the use of Fu.sarium resistant tetraploid wheat as a parent in crosses with other tetraploid wheat, as well as the Fu.sarium resistant progeny of such croSSes.
Optionally, members of the backcrossed progeny (BC,FZ) are then selected using selection criteria that can include, but are not limited to, plant features such as plant type, fertility, plant height, head type, maturity, kernel type, and the like. Selected members of the backerossed progeny (BC,F~) are then selfed to produce additional (BC,F~) progeny, which are selected using selection criteria and selfed to produce (BC,F~) progeny. This process is continued until tetraploid wheat is produced that has increased Fusariunu resistance, and other plant features that were selected. This process may be repeated until tetraploid wheat is produced having the selected plant features. In some examples, selfed progeny are produced by performing one to seven selfings, one to ten selfings, one to twenty selfings, and single integer selfings thereof. Examples of such single integer selfings include (BC,F6), (BC~F~), (BC,Fg), (BC,F9), (BC,F,o), (BC,Fii), progeny and so on.
In a preferred embodiment of the method of producing F usarium resistant tetraploid wheat, the Fz population is Large in number (e.g., more than 2000 members, preferably more than 3,000 members, most preferably more than 4,000 members) and a relatively Large number of those members (e.g., over 100, preferably over 200) are selected for selfing. Families F3, F4, F5, F6, F~, Fg, F9, and so on, are also large compared to standard breeding protocols. The large size of the families increases the probability of a recovery of a line that has Fusarium resistance. Selection within a family, even if the family is 98%
genetically identical, surprisingly yields plants with genetic differences.
Some

9 of these selected plants exhibited Fcr,saricrm resistance. Most breeders do not select within FS families because of the little genetic diversity present in these families, as they have reached 96.87590 homozygosity. However, as described herein in Example l, the little genetic variability present in the BC,FS
generation was productively explored.
As shown in Example l, tetraploid wheat produced through transfer of Fu,rariun2 resistance from hexaploid wheat to the tetraploid wheat according to this method exhibit a F'u.sarium disease severity of about 7~/o to about 16%
in greenhouse testing and about l2~lo to about 32010 in field testing.
The present invention is illustrated by the following examples. It is to be understood that the particular examples, materials, amounts, and procedures are to be interpreted broadly in accordance with the scope and spirit of the invention as set forth herein.

10 EXrIMPLES
Example I. Preparation of FHB resistant tetraploid wheat Summary Tetraploid wheat that was not resistant to Fusarirrm was crossed with Fusarium resistant hexaploid wheat. The progeny were then backcrossed with tetraploid wheat to produce backcrossed F, (BC,F,) progeny. The backcrossed F1 progeny were then selfed to produce backcrossed progeny (BC,F~) that include the Frr.sarium resistant tetraploid w-heat.
Materials Sceptre and Medora durum wheat were developed by the Department of Plant Science and Plant Pathology at the University of Saskatchewan and were I S released on 5 July 1985 and May, 1982, respectively. Sceptre and Medora exhibit high yield and quality but do not exhibit Fusarir~m resistance. A
complete description of Sceptre has been published (Knoll, Can. J. Plant Sei., 66:407 (1986)). A complete description of Medora has also been published (Leisle, Call. J. Plant Sci., 66:999 ( 1986))_ Ben durum wheat was developed by the North Dakota Agricultural Experiment Station in cooperation with USDA-ARS and released in March of 1996. Ben was registered and was protected under the U.S. Plant Variety Protection Act for Foundation, Registered, and Certified seed classes (PVP
Certificate no. 9700089) (Elias et al., Crop Science, 38:895 ( 1998)). Ben durum wheat also does not exhibit Fusarium resistance.
The durum experimental lines D88096, D88816, D88090 and D88690 were developed by the Durum Wheat Breeding Program at North Dakota State University for possible release as varieties. These wheat varieties also do not exhibit Fusarium resistance.

Methods The tetraploid wheat varieties Sceptre. Medora, and Ben. and the tetraploid experimental lines D88096, D888I6. D88090 and D88690 were crossed and backcrossed with the Fu.sarium resistant hexaploid wheat, Sumai 3 or Wnagshuibai, to produce FHB resistant tetraploicl durum wheat.
Specifically, Sumai 3 was crossed to Sceptre (Sumai 3/Sceptre) and Medora (Sumai 3/Medora). Wnagshuibai was crossed to Ben (WnagshuibailBen).
The F, resulting from the Sumai 3/Sceptre cross was backcrossed to the four durum experimental Lines, D88096, D88816, D88090 and D88690, to generate four different backcrosses F, (BC,F,) Sumai 3/Scepire//D8896, Surnai 3/Sceptrel/D88816, Sumai 3/Sceptre//D88090, and Sumai 3/Sceptre//D88690.
The F, resulting from the Surnai 3/Medora cross was backcrossed to Medora to generate backcross F, (BC,F,) Medora//Surnai 3/Medora.
The F, resulting from the Wnagshuibai/Ben cross was backcrossed to Ben to generate backcross F, (BC,F,) WnagshuibaiBen//Ben.
The purpose of the backcross is to reconstitute the tetraploid background.
All BC,F, wheat were selfed to produce BC,F~ progenies.
The BC,F, progenies were planted in a field and single head (spike) selections were made from the BC,F~ generation for durum plant type, fertility, plant height, head type, maturity, kernel type, and other agronomic traits.
BC,F3 head rows were made following these selections. At the BC,F~_further selections were made from the BC,F3 generation for the same traits described earlier. First selection was practiced among head rows then within each selected head row the best two plants were selected and planted as sister head rows in the next generation. The BC,F4 head rows were made from these selections. A
similar selection procedure to the BC,F3 generation was practiced to develop the BCrFs generation.
The BC,FS generations were planted as head hill plots (20 seed/hill) in a field Fusarium head blight nursery at Prosper, North Dakota for FHB evaluation and selection.
Corn colonized with F. gramine~zri~m (grain spawn) was used as a source of inoculum in the nursery. The grain spawn was spread onto the ground by hand at a rate of 40 grams/meterz. The first spawn was spread when the durum wheat was about twc> w -eekl from flowering. Additional fresh spawn was spread when needed. The nursery was equipped with a misting system to keep humidity at optimum level for disease development.
First selection was practiced for FHB resistance among head hill plots.
_5 Then, within each selected hill plot, the best six plants were selected and planted as sister head rows (BC,F6) in the next generation.
The BC~F6 generations were planted as head rows in a Fusarium head blight nursery at the Academy of Agricultural Sciences. Plant Protection Institute Shanghai, China, (AASPP1S). Twenty kernels from each accession were planted in single l .5 meter long rows. Entries were assigned to experimental units using a modified augmented block design. Two to three weeks prior to flowering, rice and wheat kernels infected with F. graminearum were spread by hand onto the ground to create an artificial epidemic. The nursery was equipped with a misting system to keep humidity at the optimum level for disease development.
Resistant rows were selected and then BC,F~ heads from the selected head rows were selected, threshed, and shipped back to North Dakota State University.
The BC,F~ heads w-ere planted as head rows in the nursery at North Dakota State University for FHB evaluations. Methods of inoculum preparation and inoculation in the nursery that were used are known (Stack. Can. J. Plant Path., 11:137 (I989)). The single spikelet injection method was used in which the inoculum is injected into a single spikelet near the middle of the spike near anthesis_ Plants were misted periodically to maintain high humidity for disease development. Plants were rated for Type II disease severity 3 to 3.5 weeks after inoculation using a known scale as described herein (Stack and McMullen, A
visual scale to estimate severity of FHB in wheat. No. Dak. St. Univ. Bull. P-1095 ( 1995)). Mean Type I1 disease severity of progenies from these crosses are presented in Table 2. Selected lines that are in Table 2 were planted as a randomized complete design trial with four replicates in the field in 2002 for evaluations relying on natural epidemic.
The trial was also planted in the field Fusarium head blight screening nursery at Prosper, North Dakota. Environmental conditions in 2002 were favorable for inducing a severe natural FHB epidemic. The natural epidemic provided good data for the trial that was not in the screening nursery. Data from this trial is presented in Table 3. Fusarium head blight Type II disease severity ratings of these lines in the trial ranged from 1390 to 31.S~~e.
The resulting experimental durum lines, which represent Feesal-11117?
resistant tetraploid wheat, are indicated by the following identifiers: DO1 151 l, D011502, DOl 1513, DOI 1509, DO1 1516. DO l 1522, DOl 1507, D01 1501, DOl 1519, D011524, D011510, D011506, D011512, DOl 1503, D011525, D01 1517, D011515, DOI 1508, D011518, DO l 1521, D01 1514, DOl 1523 and D01 1520 as described herein.
Mitotic Chromosome Observation All lines generated from the crosses were checked for chromosome number to insure their ploidy level and check for any abnormalities such as monosomics or chromosome additions. Seeds of the durum wheat lines were germinated on wet filter paper in a petri-dish at 25°C. Roots that were 2-3 cm long were collected and treated in ice water for 20 hours. The roots were then fixed in a solution of 3: I (9507oalcohol:glacial acetic acid). The roots were stained with 2070 acetocarmine at room temperature for 1-2 hours before chromosome preparation. Mitotic chromosomes were prepared following known procedures (Cai and Liu, Theor. Appl. Genet., 77:81 ( 1989)). Mitotic chromosomes in each of the durum lines were counted under an Olympus microscope. All lines were found to have 14 pairs of chromosomes without any abnormalities indicating that they are tetraploid wheat.
Molecular Markers for FHB Resistance Identification of DNA markers associated with FHB resistance is thought to be a useful tool for wheat breeders working on developing FHB resistant wheat germplasm. A considerable number of mapping studies have been conducted on the Type II resistance of Sumai 3 and its derivatives. A major quantitative trait loci (QTL) was identified in Sumai 3 and designated as Qfhs.ndsu-3BS that is widely used by wheat breeders in the United States. A
SSR (Simple Sequence Repeats) marker Xgovm533 that explains 41.6% of the variation of FHB resistance associated with this QTL has been identified (Anderson et al., Theor. Apl. Genet., 102:1161 (2001 )). Many breeding programs are using the Xgwm533 marker to check the presence of this QTL in their germplasm. The Xgw~n533 was also used to check the presence of the Sumai 3 QTL in the progenies of the hexaploid by tetraploid crosses.
For DNA extraction, a Flinders Technology Associates (FTA) plant purification protocol was used. Leaf tissue was collected at the three leaf stage and smashed onto the FTA cards. Cell membranes and organelles in the leaf tissue were lysed and DNA becomes entrapped in the fibers of the FTA matrix due to being smashed onto the FTA cards. A 2.0 Inns punch from within the middle of the smashed leaf stain was removed using a 2.0 mm Harris Micro Punch tool and transferred to an appropriate PCR amplification tube. Each punch was washed twice with 200 LtL of FTA reagent followed by an equal number of washings with TE 10 mM Tris-Hcl pN 8.0; 0.1 mM EDTA ph 8Ø
The punch was then dried at room temperature for 3 hours and then used for PCR amplification. The presence or absence of the marker in the lines is reported in Table 2 and Table 3.

Table 2 Fusarium head blight percent mean disease severity and presence (+) or absence (-) of the marker X~vvm533 of durum lines evaluated in a greenhouse in the Spring of 2000 Entry Label Pedigree ~e Disease XgN'mS33 Severity 28 DOl 1511 Sumai 3/Sceptre//D888167.0 29 D011502 Sumai 3/Sceptre//D888167.0 69 D011513 WangshubaiBen/Ben 7.0 +

20 DOl 1509 Sumai 3/Sceptre//D886907.4 -80 D011516 WangshubaiBen//Ben 8.0 95 DOl 1522 Medora//Surnai 3/Medora8.1 7 DOl 1507 Sumai 3/Sceptre//Sceptre8.3 13 DO11501 Sumai 3/Sceptrel/D880968.4 88 D011519 Wangshubai/Ben//Ben 8.4 l D01 1524 Sumai 3/Sceptre//Sceptre8.5 -25 D011510 Sumai 3/Sceptre//D888169.0 I DOI 1506 Sumai 3/Sceptrc//D880909.2 66 DOl 1512 Scepire/Sumai 3//Sceptre9.2 30 D011503 Sumai 3/Sceptre//D888169.5 I D011525 Sumai 3/Sceptre//D888169.7 97 D011517 WangshubaiBen/Ben 10.0 +

80 D0115I5 WangshubaiBen/Ben 109 +

DOl 1508 Sumai 3/Sceptre//D88096I I.9 -86 D011518 Wangshubai/Ben//Ben 13.0 -94 DOl 1521 Medora//Sumai 3/Medora13.0 -75 D011514 WangshubaiBen/Ben 13.2 100 DOI 1523 Medoral/Sumai 3/Medora13.5 91 D011520 Wangshubai/Ben//Ben 15.8 -170 D91103 Mod. Res. Check 24.6 171 D88541 Susceptible Cheek 60.6 LSD 18.3 (0.05) *As shown in Figure I and 2, a smaller % disease severity value indicates greater resistance to Fu.iarium infection.
Table 3 Mean days to heading (DTHD), height, Fusarium head blight disease severity, and presence (+) or absence (-) of the marker Xgwm533 of lines tested in a Prosper, North Dakota field test.
Entry 1_abel Pedigree DTHD height cm Disease X~~~''~1533 Severity 25 D011525 Sumai 52.3 99.0 11.7 3/Sceptre//D88816

11 DO11511 Sumai 53.0 96_5 13.5 +

3/Sceptre//D88816 6 D011506 Sumai 52.3 106.0 16.2 +

3/Sceptre//D88090 9 D011509 Sumai 52.5 102.8 16.2 3/SceptrellD88690

12 D0115I2 Sceptre/Sumai 50.3 101.3 18.0 3//Sceptre DOII510 Sumai 52.5 96.5 20.7 3/Sceptre//D88816 17 D011517 WangshubaiBen/Ben50.8 103.3 22.5 8 D011508 Sutnai 50.0 93.8 25.2 -3/Sceptre//D88096 29 Belzer Mod. Res. Check 53.0 96.0 25.2 21 D011521 Medora//Sumai 49.5 97.0 25.2 3/Medora 14 D011514 WangshubaiBen/Ben50.8 103.3 25.2 +

D011520 WangshubaiBen/Ben50.8 106.5 25.2 24 DOII524 Sumai 54.3 87.3 27.0 3/Sceptre//Sceptre 7 D011507 Sumai 53.0 89.5 27.0 3/Sceptre//Sceptre 1 DOl 1 Sumai 51.3 95.0 27.0 3/Sceptre/lD88096 23 D011523 Medora//Sumai 49.8 95.8 27.0 3/Medora

13 D011513 WangshubaiBen/Ben49.8 97.0 27.0 l9 D011519 WangshubaiBen/Ben48.3 106.5 27.0 18 D011518 WangshubaiBen//Ben47.8 107.3 27.0 31 Maier Mod. Susceptible 52.0 88.3 29.7 Check IS DOI1515 WangshubaiBen/Ben49.5 96.0 29.7 16 D011516 Wangshubai/Ben/Ben47.5 99.5 29.7 30 D9l 103 Mod. Res. Check 51.8 100.8 29.7 22 D011522 Medora//Sumai 48.5 103.3 29.7 3/Medora 2 D011502 Sumai 50_S 88.5 31.5 3/Sceptre//D888I6 3 D011503 Surnai 51.3 90.0 31.5 3/Sceptre//D888I

28 Rugby Mod. Susceptible 51.3 100.3 36.0 Check 1.2 S.S 1.0 LSD, (0_OS) CV, 1.7 4.0 25.5 *As shown in Figure l and 2, a smaller % disease severity value indicates greater resistance to Fusariurn infection.
The complete disclosures of all patents, patent applications including provisional patent applications, and publications, and electronically available S material (e_g_, GenBank amino acid and nucleotide sequence submissions) cited herein are incorporated by reference_ The foregoing detailed description and examples have been provided for clarity of understanding only. No unnecessary limitations are to be understood therefrom. The invention is not limited to the exact details shown and described: many variations will be apparent to one skilled in the art and are intended to be included within the invention defined by the claims.

Claims (27)

What is claimed is:

1. A method for making Fusarium resistant tetraploid wheat comprising:
crossing hexaploid Fr,r.sarium resistant wheat with tetraploid wheat to produce F1 progeny, backcrossing the F1 progeny with tetraploid wheat to produce a backcrossed F1 (BC1F1) progeny, and selling the backcrossed F1 (BC1F1) progeny to produce a backcrossed progeny (BC1F2) comprising the Fusarium resistant tetraploid wheat.

2. The method of claim 1 further comprising using selection criteria to prepare a further nth selected (BC1F n) BC1F3) progeny from the selfed (BC1Fn-1) progeny, where n is equal to or greater than 3.

3. The method of claim 2 wherein the selection criteria comprise plant type, fertility, plant height, head type and/or maturity.

4. The method of claim 2 wherein the selection criteria comprise Fusarium resistance.

5. The method of claim 1 wherein the hexaploid Fusarium resistant wheat comprises a wheat variety selected from the group consisting of Sumai 3, Wnagshuibai, Ning 7840, Frontana, Nobeokabouza, 2375, Ernie and Freedom.

6. The method of claim 1 wherein the tetraploid wheat comprises a wheat selected from the group consisting of Sceptre, Medora, Ben, D88096, D88816, D88090, D88690, Munich, Belzer, Mountrail, Maier, Lebsock, Plaza, Pierce, and Dilse.

7. Fusarium resistant tetraploid wheat produced according to the method of claim 1.

8. Progeny or seed of the Fusarium resistant tetraploid wheat of claim 7.

9. Fusarium resistant wheat grown from the seed of claim 8.

10. Progeny or seed of the Fusarium resistant tetraploid wheat of claim 9.

11. Fusarium resistant tetraploid wheat characterized by a disease severity in a Type II infection assay of less than 20%.

12. Progeny or seed of the Fusarium resistant tetraploid wheat of claim 11.

13. Fusarium resistant wheat grown from the seed of claim 12.

14. Progeny or seed of the Fusarium resistant tetraploid wheat of claim 13.

15. Fusarium resistant tetraploid wheat characterized by a disease severity in a Type II infection assay of less than 7%.

16. Progeny or seed of the Fusarium resistant tetraploid wheat of claim 15.

l7. Fusarium resistant wheat grown from the seed of claim 16.

18. Progeny or seed of the Fusarium resistant tetraploid wheat of claim 17.

19. Fusarium resistant tetraploid wheat comprising a genome resulting from a cross between tetraploid wheat and Fusarium resistant hexaploid wheat, followed by a backcross to tetraploid wheat.

20. The Fusarium resistant tetraploid wheat of claim 19 wherein the genome results from a cross between tetraploid wheat and Fusarium resistant hexaploid wheat variety selected from the group consisting of Sumai 3 and Wnagshuibai.

21. The Fusarium resistant tetraploid wheat of claim 19 wherein the genome results from a cross between tetraploid wheat variety selected from the group consisting of Sceptre wheat, Medora wheat and Ben wheat, and a Fusarium resistant hexaploid wheat.

22. The Fusarium resistant tetraploid wheat of claim 19 wherein the genome results from a backcross to a tetraploid wheat variety selected from the group consisting of D88096, D88816, D88090, Medora and Ben.

23. Progeny or seed of the Fusarium resistant tetraploid wheat of claim 22.

24. Fusarium resistant wheat grown from the seed of claim 23.

25. Progeny or seed of the Fusarium resistant tetraploid wheat of claim 24.

26. A method for using Fusarium resistant tetraploid wheat comprising:
crossing a first tetraploid wheat which is Fusarium resistant with a second tetraploid wheat exhibiting at least one desired trait, to yield Fusarium resistant tetraploid wheat exhibiting the desired trait.

27. The method of claim 26 wherein the second tetraploid wheat exhibits more or less Fusarium resistance than the first tetraploid wheat.