WASHINGTON
USDA-ARS, WHEAT GENETICS, QUALITY, PHYSIOLOGY AND DISEASE RESEARCH UNIT
Departments of Crop & Soil Sciences, Food Science and Human Nutrition, and Plant Pathology, Washington State University, Pullman, WA 99164, USA.
M.K. Walker-Simmons, Craig F. Morris, R.E. Allan, Camille M. Steber,
Kimberly Garland Campbell, Xianming M. Chen, Roland F. Line, L.D.
Holappa, Todd Linscott, Benjamin Rangel, Ryan Wagner, Janice M.
Zale, John A. Pritchett, Lynn M. Little, Scott W. McDonald, A.D.
Bettge, H.C. Jeffers, H-G. Chang, T. Demeke, M.C. Simeone, M.
Lillemo, D.A. Engle, G.E. King, B. Patterson, M. Baldridge, B.
Davis, R. Ader, David Wood, Mary Moore, and Guiping Yan.
R.E. Allan.
Backcross-derived NILs with the RhtB1c gene (Rht3) of Tom Thumb were developed in six northwestern U.S. winter wheat varieties. The varietal backgrounds and their plant height genotypes were Moro, Brevor, Olympia (RhtB1a RhtD1a); Stephens (RhtB1b RhtD1a); Daws and Tres (RhtB1a RhtD1b). RhtB1b and RhtD1b are the new symbols for Rht1 and Rht2, respectively. Agronomic comparisons were made between NILs of all possible plant height phenotypes based on three or four field tests at Pullman during 1996 and 1997.
The RhtB1c gene reduced height by 48-67 % compared to NILs in which it was lacking. Plant heights of NILs with RhtB1c RhtD1a averaged 35-67 cm versus 108-141 cm for NILs with RhtB1a RhtD1a. NILs individually having RhtB1c and RhtB1b and RhtD1b genes had means of 47, 81, and 89 cm, respectively. NILs with both RhtB1c and RhtD1b averaged 33 cm versus 49 cm for NILs with RhtB1c alone.
Among tall varieties, Moro, Olympia, and Brevor the RhtB1c gene reduced height 51, 52, and 67 %, respectively. The Stephens RhtB1c RhtD1a NILs were 48 % shorter than their RhtB1b RhtD1a sibs. Four height phenotypes comprised the Tres and Daws NILs. Those with RhtB1c RhtD1b were 63 % shorter than sibs having the RhtB1a RhtD1b genotype of Tres and Daws. Tres and Daws NILs with RhtB1c RhtD1a were 42 and 49 % shorter than RhtB1a RhtD1b sibs, respectively. Tres and Daws NILs lacking both RhtB1c and RhtD1b (RhtB1a RhtD1a) were 19 to 43 % taller than NILs having the RhtB1a RhtD1b genotypes, respectively.
Other traits measured included heading date, grain yield, harvest index, spikes/sq m, kernels/spike, kernel weight, test weight, and percent lodging. The RhtB1c gene alone or in combination with RhtD1b consistently reduced both test weight (50-95 g/l) and kernel weight (3-8 mg) of all varieties. The RhtB1c gene generally delayed heading date by 2 to 5 days when compared to NILs where it is lacking.
The effect of the RhtB1c gene on grain yield, harvest index, and kernels/spike varied among the six backgrounds. Generally NILs with RhtB1c alone or combined with RhtD1b yielded less than NILs lacking RhtB1c (13-59 % less). However, RhtB1c Olympia NILs yielded nearly 30 % more than their RhtB1a sibs. Olympia, Moro, Brevor, and Daws NILs with RhtB1c had harvest indexes 3-44 % greater than their NILs lacking the gene; Tres and Stephens NILs with RhtB1c had harvest indexes 5-20 % less than their sibs without this gene. Moro and Olympia NILs with RhtB1c had greater kernels/spike (12-33 %) than their sibs in which it was lacking. In the other four backgrounds, NILs with RhtB1c had 5-39 % fewer kernels/spike than NILs without.
The RhtB1c gene affected spikes/m2 in two backgrounds. Olympia RhtB1c NILs had 18 % more spikes than their RhtB1a NILs, whereas the Daws RhtB1c RhtD1b NILs had 20 % fewer spikes than their RhtB1a RhtD1b sibs. As expected, RhtB1c RhtD1a NILs sustained much less lodging than RhtB1a RhtD1a NILs (1-4 % versus 23-67 %). There was no lodging resistance advantage for NILs with RhtB1c versus those with RhtB1b or Rht1Db.
Although RhtB1c is a very potent dwarfing gene under northwestern U.S. conditions, it apparently lacks agronomic potential. Unlike RhtB1b and RhtD1b, RhtB1c failed to consistently enhance kernels/spike or harvest index. Negative effects on kernel weight, test weight, and grain yield out-weighed its lodging resistance potential.
Seed of NILs of the six varietal backgrounds have been deposited with the National Seed Storage Lab in Ft. Collins, CO. Small quantities of seed can also be obtained by contacting L.M. Little (lmlittle@wsu.edu).
Xianming Chen.
Wheat stripe rust and stem rust were accurately predicted for the year 2000 using monitoring data and predictive models based on environmental and crop factors such as temperature, precipitations, and resistance of wheat cultivars. Wheat stripe rust in the United States occurred from the Pacific Northwest to Virginia and from Texas to North Dakota. Severe yield losses occurred in fields of susceptible wheat in the Pacific Northwest and the southcentral states (Arkansas, Louisiana, and Texas). In the southcentral states, more fungicide was sprayed than in the last 5 years and many fields were abandoned because of stripe rust. The severe epidemics in the southcentral states and the spread of the disease to the northern and eastern states were due to the weather conditions, new races of the rust pathogen, and widely grown susceptible cultivars. Stripe rust was found early, because it overwintered in many areas in the southern United States, where the winter was milder than normal. The spring weather was cooler than normal, favoring stripe rust development. California wheat also suffered severe yield losses in 2000 because of cool weather and storms that provided moisture allowing stripe rust to increase. Wheat stripe rust at 100 % severity occurred in fields of the widely grown cultivar RSI 5. More important, a group of new races with virulences that were first detected in the United States were occurring in California and east of the Rocky Mountains.
In the Pacific Northwest, wheat stripe rust widely occurred, but yield losses were the minimum in 2000. The winter of 1999-00 was mild, favoring stripe rust overwintering. More than 90 % stripe rust was observed on susceptible entries in our stripe rust nurseries and on susceptible cultivars such as Westbred 470 in commercial fields. Dry weather in May slowed the development of stripe rust. Resistant cultivars that were widely grown in the Pacific Northwest provided effective control of wheat stripe rust. The durable, high-temperature, adult-plant resistance that is in most soft white winter wheats, hard red winter wheats, and spring wheats and the multiline cultivar Rely of club wheat with many seedling-resistance genes prevented severe stripe rust epidemics.
Because of unfavorable weather conditions, wheat leaf and stem rusts were not significant in the Pacific Northwest in 2000. Yield losses due to leaf rust were the minimum, and there were almost no yield losses due to stem rust.
Hundreds of stripe rust collections were evaluated to determine their virulence. These samples were increased on susceptible cultivars and tested on a set of cultivars that are used to differentiate races of P. striiformis f. sp. tritici in the United States. In addition to the 16 wheat differential cultivars (Lemhi, Chinese 166, Heines VII, Moro, Paha, Druchamp, Riebesel 47/51, Produra, Yamhill, Stephens, Lee, Fielder, Tyee, Tres, Hyak, and Express), supplementary differential cultivars and Yr-gene lines (Yr8, Yr9, Clement, and Compare) also were used in the tests to determine virulence. In 2000, the most prevalent races in the Pacific Northwest were those attacking Lemhi (Yr21), Fielder (Yr6, YrFie), Produra (YrPr1, YrPr2), Moro (Yr10, YrMor), Paha (YrPa1, YrPa2, YrPa3), and seedlings of Druchamp (Yr3a, YrDru, YrDru2) and Stephens (Yr3a, YrSte, YrSte2). The most prevalent races in California were Express-attacking races and races attacking Express plus varieties with stripe rust-resistance genes Yr8 and Yr9. The predominant races east of the Rocky Mountains were those attacking cultivars with Yr8, Yr9, plus Express. The Express-attacking races, which were first detected in California in 1998, were in all regions except the Pacific Northwest. The races attacking Yr8 and Yr9 were first detected in the United States and widely distributed in 2000. The number of new races of wheat stripe rust that were detected in 2000 was the most in a single year. The new races were not prevalent in the Pacific Northwest, but they may appear in the Pacific Northwest in the future. We need to consider them in the Pacific Northwest wheat breeding programs for developing stripe rust resistant cultivars.
Wheat germ plasm from the National Germplasm Collection at Aberdeen, ID and advanced lines from wheat breeders in the western United States were evaluated in the greenhouse for resistance to the most virulence races of the wheat stripe rust pathogen and at field sites for adult-plant resistance. Breeding lines with resistance to the rusts were identified. High-temperature, adult-plant (HTAP) resistance continues to be the most effective and durable type of stripe rust resistance. More than 95 % of the wheat cultivars in Washington have stripe rust resistance, and all newly released cultivars have HTAP resistance.
To obtain superior, durable resistance against stripe rust of wheat, molecular markers were identified for genes conferring high-level seedling resistance, and durable, adult-plant resistance. The resistance gene analog polymorphism (RGAP) technique that we recently developed and other molecular techniques such as microsatellite markers were used to identify markers for wheat genes for resistance to stripe rust. Unique RGAP markers were identified for NILs with Yr1, Yr5, Yr7, Yr8, Yr9, Yr10, Yr15, Yr17, Yr18, and YrA. Cosegregation of markers with Yr9 was confirmed with BC7:F2 and BC7:F3 generations of the cross between the Yr9 line and the recurrent parent. The location of Yr9 on chromosome 1B was confirmed by analyzing the nullisomic-tetrasomic and ditelosomic lines of Chinese Spring with codominant RGAP markers. The Yr9 markers also were detected in five wheat cultivars that have Yr9. BC7:F3 lines from the cross of 'Avocet S/T. spelta album' (Yr5) were used to develop molecular markers for Yr5. Based on the results of the testing the population with stripe rust races and presence of the molecular markers, 10 RGAP markers were linked with the Yr5 gene, of which five markers were tightly linked to the gene. To map QTLs for durable, HTAP resistance, the F7 lines of 'Stephens/Michigan Amber' were evaluated for resistance in field plots. Molecular markers were identified by amplifying the F8 DNA with RGAP primers. Resistance QTLs that explained the most of variation was mapped on a linkage group consisting of 10 RGAP markers. These results show that the RGAP technique can be used to identify resistance genes in germ plasm and may be used to help combine resistance genes. These markers can now be used to combine different genes for resistance and different types of resistance without losing quality.
Seed treatment and foliar spray with standard and candidate fungicides or combinations of fungicides were tested for control of smuts and rusts. Vitavax, Raxil, Dividend, Baytan, LS176 + Raxil, LS176 + Allegiance, LS176 + LS022, and Triticonazole provided good control of both seedborne and soilborne flag smut (Urocystis agropyri) at one or more of the rates tested. Dividend provided complete control and LS176 + Allegiance and LS176 + LS022 provided nearly complete control of dwarf bunt (Tilletia controversa). Vitavax, Raxil, Dividend, Baytan, LS176 + Raxil, LS176 + Allegiance, LS176 + LS022, and Triticonazole provided good control of both seedborne and soilborne common bunt (Tilletia tritici). Folicur, Tilt, Quadris, and Stratego controlled stripe rust, whereas two formulations of CGA279202 were less effective.
USDA-ARS Western Wheat Quality Laboratory
Pullman, WA 99164, USA.
Craig F. Morris. [p. 306]
We continue to work on grain hardness (texture) and are in the process of backcrossing all seven known hardness alleles into a common SWSW background. Hard and soft NILs were registered and released. A survey of North American wheats was conducted for hardness allele. We used our RIL population between Kanto 107 and Bai Huo to study the role of Waxy genes on white salted noodle texture. Full waxy selections from this cross were registered and released. Properties of waxy and normal starch granules were reported. We continued our study of polyphenol oxidase (PPO) in the context of darkening of wheat foods, especially Asian noodles. An improved L-DOPA PPO assay was reported and mapping and cloning work progressed. We collaborated on durum breadbaking and free-air CO2 free air enrichment studies.
We milled, baked, and evaluated the quality of several thousand breeder lines. We also led the PNW Wheat Quality Council that met in Seattle, and conducted the soft white wheat portion of U.S. Wheat Associates Overseas Varietal Analysis Program. Craig Morris stepped down as cochair of the AACC Asian Products Technical Committee; Art Bettge assumed chairmanship of the AACC Soft Wheat Products Technical Committee.
Morten Lillemo returned to Norway to finish his PhD; Marco Simeone obtained a positin with De Cecco pasta manufacturer in Italy; and Prof. Hak-Gil Chang completed his sabbatical and returned to Korea. Herb Jeffers retired after many productive years with the WWQL and Brenda Patterson resigned to pursue a career in eduction.
USDA-ARS Wheat Genetics [p. 307-309]
Pullman, WA 99164, USA.
Kim Garland Campbell, Camille M. Steber, Todd Linscott, Lynn Little, Karen McGuiness, Scott McDonald, John Pritchett, and Janice Zale.
Growing conditions were favorable for winter wheat in eastern Washington, northern Idaho, and northeastern Oregon in the year 2000. A mild winter was followed by a cool spring and moderate summer. Disease pressure was light. State average yields of winter wheat were 73 bu/acre in WA, 62 bu/acre in OR, and 90 bu/acre in ID. In Washington, soft white wheat was the predominant class grown with 1,455,400 acres planted, club wheat acreage increased to 12 % of the total crop or 235,000 acres.
As part of the USDA-ARS Wheat Genetics, Quality, Physiology, and Disease Resistance unit, the wheat breeding and genetics project has the objectives of the ARS breeding and genetics program are to develop improved club wheat cultivars for the Pacific Northwest; develop wheat germ plasm with better emergence, improved end-use quality, resistance to stripe, leaf, and stem rusts and soil borne disease associated with conservation tillage; and coördinate the Western Regional Nurseries.
In 2000, 367 crosses were made in the greenhouse, 154 F2 populations and 37,000 head rows were visually evaluated at Pullman, 1,000 F4 entries were evaluated in unreplicated yield plots, and 313 entries were evaluated in replicated yield trials at multiple locations in Washington and Oregon. Locations included Bickelton, Central Ferry, Connell, Harrington, Lind, Pomeroy, Pullman, Ritzville, in Washington plus Lexington, Echo, Moro, and Pendleton in Oregon. Separate disease nurseries were established to evaluate resistance to foot rot (Tapesia yallunde) and stripe rust. The WSU winter wheat breeding program, the WSU variety testing program, and personnel at the Columbia Basin Agricultural Research Center in Pendleton OR assisted in the planting and harvest of several nurseries.
Twenty-seven entries were evaluated in the Western Regional
Hard Winter Wheat Nursery, 35 entries in The Western Regional
Soft Winter Wheat Nursery, and 39 in the Western Regional Spring
Wheat Nursery. The complete report for agronomic data is available
at on the web through the graingenes gopher at gopher://greengenes.cit.cornell.edu/11/.Performance/.westregional.
Five breeding lines were sent to the 2001 regional nurseries.
Four club wheats, ARS 9658, ARS97119, ARS97123, and ARS98237,
were entered for the first time. ARS97119 and ARS97123 are sister
lines. The SWWW ARS96277 was reëntered. All five entries
have both foot rot resistance derived from VPM and resistance
to stripe rust from various sources.
A SWWW, WA7853, approved for release and named Finch. The cultivar
was released as a complement to Madsen, as second soft white wheat
with resistance to foot rot and stripe rust. Finch has better
end-use quality and superior yields to Madsen. A white club wheat,
WA7855, was approved for prerelease seed increase and named Chukkar.
The wheat was released as a high yielding club wheat for eastern
Washington and northern Idaho. Chukkar has resistance to foot
rot and stripe rust plus good agronomic characteristics for the
higher rainfall areas of the Pacific Northwest. Chukkar has excellent
club wheat milling and baking quality and has exhibited yields
superior to those of Madsen in our testing area.
In our project to improve emergence of winter wheat from deep furrow seedling, we used the SSR marker Xgwm622 to screen advanced breeding lines for the presence of Rht8. We have lost Rht8 in most lines. We suspect it was lost because of its linkage to Ppd1 and our tendency to select for photoperiod sensitivity in our environment. We have identified one breeding line with Rht8 and will be evaluating it for photoperiod sensitivity this spring.
In our project to evaluate winter hardiness of winter and spring cultivars in the PNW, we are determining LT50 ratings using freeze testing. Cultivars commonly grown in the PNW have LT50s in the range of -7 C to -18 C.
We are in the process of doing preliminary experiments to use
the maize Ac/Ds transposable elements to clone genes
in wheat. We found that the Ac/Ds transposon is
not detectable in low stringency Southern blots using the second
exon of the transposase as a probe. However, if we search the
wheat EST database we do find an Ac-like homologue. The
homology, in this case, is strong at the amino acid level, but
weaker at the DNA level.
We have discovered that the plant hormone brassinosteroid has
a stimulatory effect on germination. Initial experiments were
performed using GA mutants in Arabidopsis. Future efforts
will examine whether brassinosteroid signaling also plays a role
in wheat preharvest germination and in emergence.
WASHINGTON STATE UNIVERSITY
Spring Wheat Breeding and Genetics Program, Department of Crop and Soil Sciences, 201 Johnson Hall, Pullman, WA 99164-6420, USA.
K. Kidwell, G. Shelton, V. DeMacon, B. Barrett, J. Smith, J. Baley, and C. Bickle.
The overall goal of wheat breeding efforts at WSU is to enhance the economic and environmental health of wheat production in the PNW by releasing genetically superior varieties for commercial production. Traditional breeding methods and molecular genetic technology are combined to reduce production risks associated with abiotic and biotic stresses by incorporating genetic insurance into adapated, elite varieties.
K. Kidwell, G. Shelton, and V. DeMacon.
Over 350 crosses were made in 2000, and nearly 35,000 breeding lines were evaluated in field trials at 116 locations. F1 seed from 354 lines was increased to generate segregating progenies for use in conventional breeding strategies, MAS, and gene linkage analyses. Approximately 280 F2 and 300 F3 families were advanced to the next generation, and over 3,000 entries among 31,360 F4 head rows were selected, based on stripe rust reaction and phenotype, for early generation end-use quality assessment. Following phenotypic selection, grain from selected head rows was visually evaluated for plumpness. Selections with sound grain were separated by market class, then entries from each market class were subjected to a specific assessment strategies depending on end-use goals. Grain protein content and grain hardness was determined on whole grain flour using the Technicon (NIR). Microsedimentation and flour swelling volume were used to assess protein and starch quality, respectively, of selected lines. The MicroMill was used to assess flour yields of early generation soft white entries. Polyphenol oxidase levels also were determined for soft white and hard white material to assess noodle color potential before selecting lines to advanced to 2001 field trials. Grain samples from 765 breeding lines with superior agronomic performance were sent to the USDA-ARS Western Wheat Quality Laboratory (Pullman, WA) for milling and baking evaluations.
Variety releases and prereleases. Two varieties, Zak
(SWSW) and Tara (HRSW) were released. Zak is a high yielding,
Hessian fly-tolerant, stripe rust-resistant variety with exceptional
baking properties that is well adapted to the high rainfall regions
of the PNW. Foundation seed (246,000 lb) of Zak was sold for producing
Registered seed in 2001. Tara is a high yielding, Hessian fly-resistant
line with exceptional gluten strength that is well adapted to
direct seed production. Foundation seed of Tara will be produced
in 2001. Local, domestic markets for both varieties are evolving
due to their exceptional end-use quality.
Two varieties, WA7902 (spring club) and WA7899 (HWSW) were approved for prerelease. WA7902 has outstanding yield potential, excellent quality and is stripe rust resistance. This variety is intended to replace Calorwa in the intermediate to high-rainfall regions of eastern Washington. Breeder seed of WA7902 will be produced in 2001. WA7899, the first hard white wheat variety to be released by WSU, has dual purpose potential. WA7899 has outstanding bread baking quality, excellent noodle color, and soft noodle texture. This wheat is moderate to high yielding, moderately resistant to stripe rust, and may be resistant to the Hessian fly. Foundation seed of WA7899 will be produced in 2001.
B. Barrett, C. Bickle, and K. Kidwell.
A rapid plant advancement protocol was developed by which plants are forced to go from seed to seed within a 10-12 week period in the greenhouse. We can advance progeny of a single cross through 4-5 generations per year, which greatly accelerates the breeding process. A wheat microsatellite marker associated with a chromosomal segment that confers a 1-2 % grain protein content (GPC) increase in two donor lines, GluPro and ND683, was identified, then a strategy was developed to rapidly move this segment into adapted germ plasm through marker-assisted backcross breeding. Initial crosses between the protein segment donor parents and the adapted hard red varieties Scarlet and Tara were made in 1998. The goal is to recover lines nearly identical to Scarlet and Tara with the addition of the increased GPC segment from the donor parents. BC5 lines containing 99 % of the genes from the WSU lines and 1 % of the genes from the donor parents, including the high protein segment, have been developed using this strategy and will be evaluated in the field, seed quantities permitting, in 2001. Field evaluations of BC1 and BC2 lines generated in initial stages of backcrossing were conducted in crop year 2000. Twelve lines from each of 24 BC1 families and 35 BC2 families derived from a subset of the original BC1s were evaluated in a nonreplicated headrow field nursery in Pullman, WA. Eighty-nine percent of the lines containing the selected markers exhibited higher GPC than the recurrent parent.
J. Smith and K. Kidwell.
Rhizoctonia root rot is a prominent disease of spring cereal grains in direct seed management systems in the PNW. To date, genetic resistance to this disease has not been identified in cultivated wheat or barley. The objectives of this study are to 1) determine whether current spring wheat and spring barley cultivars vary in their levels of susceptibility to R. solani AG-8; and 2) identify potential gene donors among wild relatives of wheat for use in cultivar improvement. Fifteen spring wheat cultivars, ten H. villosa accessions, H. villosa/durum amphiploids, Agropyron amphiploids, and H. villosa addition lines were evaluated for disease reaction to R. solani AG-8 in growth chamber analyses. Variation for disease reaction was detected among spring wheat varieties; however, all were rated as susceptible to Rhizoctonia root rot. The addition lines. amphiploids, and synthetic wheat varieties also were susceptible to infection by Rhizoctonia. Disease ratings for the H. villosa accessions were significantly lower than those for spring wheat varieties evaluated in growth chamber analyses. Although H. villosa can withstand Rhizoctonia infection, the ability to recover viable offspring from crosses between hexaploid wheat and H. villosa has been challenging. Unfortunately, other wild relatives evaluated in this study that perhaps would be more compatible with hexaploid wheat for crossing purposes, were not resistant to the pathogen. Variation in disease reaction among the varieties evaluated in this study suggests that current spring wheat cultivars may varying in their levels of susceptibility to Rhizoctonia root rot. We are currently assessing whether growth chamber results agree with resistance ratings and grain yields from inoculated field evaluations.
J. Baley, T. Paulitz and K. Kidwell.
Herbicides are an integral tool in the management of weeds in wheat production, especially in direct seeded systems. Genes are being incorporated into wheat varieties for tolerance to glyphosate, a widely used broad-spectrum herbicide. This technology has been quickly adopted in soybean and canola cultivation in North America, and has the same potential in wheat production. Introgressed transgenes code for an altered enyzme in the shikimic acid pathway that confers resistance to the herbicide, however, this same pathway is used by the plant for defense against soilborne pathogens. The objectives of the study are to examine the response of glyphosate tolerant and sensitive lines to three common root pathogens, G. graminis var. tritici, R. solani, and Pythium spp., in the presence and absence of glyphosate. The levels of key defense enzymes and products also will be determined. Glyphosate can cause a synergistic reaction with soilborne pathogens, leading to a breakdown of plant defense and increased disease on sensitive plants. Dying grassy weeds and volunteers within a crop of glyphosate tolerant wheat may serve as a reservoir of inoculum, potentially increasing disease pressure on susceptible wheat. The overall goal of this research is to proactively determine the practicality of incorporating glyphosate tolerant wheat into direct seed, agricultural production systems.