WASHINGTON
USDA-ARS, WHEAT GENETICS, QUALITY, PHYSIOLOGY AND DISEASE RESEARCH UNIT AND WASHINGTON STATE UNIVERSITY
Departments of Crop & Soil Sciences, Food Science and Human Nutrition, and Plant Pathology, Washington State University, Pullman, WA 99164, USA.
Daniel Z. Skinner, Kwang-Hyun Baek, and Brian S. Bellinger.
Manganese superoxide dismutase. The over-expression of the antioxidant enzyme manganese superoxide dismutase (MnSOD) has been shown to confer increased tolerances of environmental stresses in various plants. Using quantitative RT-PCR, we have determined that wheat MnSOD mRNA transcript levels increase rapidly in response to cold temperature and maintain elevated levels of expression through 4 weeks of cold acclimation (Baek and Skinner 2003). We have determined that the wheat genome contains several copies of the MnSOD gene that differ in DNA sequence, some of which express much more strongly in response to cold than others. We are in the process of screening a hexaploid wheat, BAC library for multiple copies of the MnSOD gene in order to elucidate the primary structure of these genes. Knowledge of the molecular structure of the cold responsive MnSOD genes will provide fundamental knowledge on structural characteristics of cold responsive genes.
We developed a method of using quantitative RT-PCR and MnSOD gene primers for quantifying the change in the amount of total RNA following exposure to cold temperature, but is applicable to any treatment. The method was verified using primers for a second gene, phospholipase D (Baek and Skinner 2004).
Evaluation of phospholipid changes during cold acclimation of wheat. Wheat undergoes many changes during the process of cold acclimation, including numerous changes in the levels of phospholipids. We evaluated the levels of 34 phospholipids in a 5-parent diallel cross of winter wheat over a 5-week, cold-acclimation period. Increased concentrations of all phospholipids were measured in response to a 1-week exposure to cold temperature. Some of the phospholipids maintained the elevated expression levels throughout the 5-week period, whereas others declined after the first week of cold exposure. Several differences were found in rates of accumulation and loss among the different populations.
Statistical analysis of the diallel data is expected to provide information on the genetic control of phospholipid accumulation and loss during cold acclimation.
Xianming Chen, Paul Ling, David A. Wood, Mary K. Moore, and Vihanga Pahalawatta.
Monitoring rusts, predicting epidemics, assessing yield losses, and identifying races of Puccinia striiformis f. sp. tritici. Wheat stripe rust, leaf rust, and stem rust were monitored throughout the Pacific Northwest (PNW) using trap plots and field survey. The diseases were accurately predicted for the PNW in 2003 using monitoring data and predictive models based on environmental factors such as temperature, precipitations, and resistance of wheat cultivars. Through coöperators in many other states, wheat stripe rust was monitored throughout the United States. In 2003, wheat stripe rust occurred in more than 25 states from Washington State to Florida and from Texas to Ontario, Canada. Severe yield losses caused by stripe rust occurred in the PNW, California, Texas, Louisiana, Arkansas, Oklahoma, Kansas, Nebraska, Colorado, and South Dakota. In 2003, stripe rust epidemic caused wheat yield losses of 88.88 million bushels plus multimillion dollars on fungicide application in the United States.
In the PNW, wheat stripe rust occurred earlier than normal on winter wheat and spread quickly on spring wheat in 2003. The dry weather conditions from early June slowed the epidemic development. Foliar application of fungicides in the fields of susceptible winter and spring wheat cultivars prevented major yield losses. The impact of the epidemic was assessed based on rust severities and yield losses of major cultivars in the experimental plots and rust survey in commercial fields. In the state of Washington, stripe rust caused 1.5 % yield loss of winter wheat production and 3.5 % yield loss of spring wheat production. The widely grown winter wheat cultivars such as Eltan, Madsen, Rod, and Stephens, and spring wheat cultivars like Alpowa, which have various levels of high-temperature, adult-plant (HTAP) resistance, prevented the most devastating epidemic that could have occurred if the resistant cultivars had not been grown. Widely grown resistant cultivars and use of fungicides in fields grown with susceptible cultivars reduced yield losses to 3.1 million bushels (1.1 %) in the PNW. In 2003, wheat leaf rust was severe in the northwest of Washington but was light in the major wheat production areas in eastern Washington, and stem rust was absent due to the dry weather conditions from early June. The nurseries of single-gene lines with leaf rust and stem rust resistance genes were covered with stripe rust. Leaf and stem rusts did not cause significant yield losses in the PNW.
More than 400 wheat stripe rust samples from wheat fields and grasses collected in the PNW and sent by cooperators throughout the US were evaluated to determine their virulence. These samples were increased on susceptible cultivars and tested on a set of 20 wheat genotypes that are used to differentiate races of P. striiformis f. sp. tritici in the US. From the collections, 25 previously identified and 13 new races were detected. Of the 38 races, only eight (PST-77, 78, 79, 80, 97, 98, 99, and 100) had frequencies more than 1 %. The eight races that counted for 89.9 % of the collections belong to a group of races with common virulences on Lemhi, Lee, Fielder, Express, Yr8, Yr9, Clement, and Compair). The group of the races were first detected in 2000 and caused severe epidemics from 2000 to 2003 in the US. In 2003, races PST-98 (virulent on Lemhi, Heines VII, Produra, Stephens, Lee, Fielder, Express, Yr8, Yr9, Clement, and Compair) and PST-100 (virulent on Lemhi, Heines VII, Produra, Yamhill, Stephens, Lee, Fielder, Express, Yr8, Yr9, Clement, and Compair) were the most predominant, each of these two races counting for 29.5 % of the samples throughout the United States.
Leaf rust samples were collected and sent to the Cereal Disease
Laboratory in the University of Minnesota. In 2003, two races,
MBGJ (virulent on Lr1, Lr3a, Lr11, Lr10,
and Lr14a) and MCDS (virulent on Lr1, Lr3a,
Lr26, Lr17, LrB, Lr10, and Lr14a)
were detected in the PNW. Race MBGJ occurred previously in 2002.
Evaluating wheat germ plasms and breeding lines for resistance to rusts and other foliar diseases. In 2003, we evaluated more than 13,000 winter and spring wheat entries including germ plasm, genetic populations, and breeding lines from the National Germplasm Collection Center and wheat breeders in the greenhouse for resistance to selected predominant stripe rust races and/or at various field sites for resistance to naturally occurring races. The wheat entries also were evaluated for resistance to leaf rust, powdery mildew, and physiological leaf spot in field sites where these diseases occurred naturally. Germ plasms and breeding lines with resistance to the disease especially stripe rust were identified. We have provided the information to breeders for developing resistant cultivars. Germ plasms were selected for further characterization of resistance and used to develop adapted lines for determine virulence of the stripe rust population and for breeding programs to develop cultivars with superior resistance.
Determining genetics of resistance and develop molecular markers for stripe rust resistance genes. To develop adapted resistant germ plasms, determine genetics of resistance, and develop molecular markers for genes conferring resistance to stripe rust, crosses and backcrosses were made with Alpowa, Express, IDO377s, Zak, Yr5, Yr15, Yr18, and Avocet Susceptible (AVS) in the field and greenhouse. Alpowa and Express have different levels of durable HTAP resistance to stripe rust. IDO377s has high level seedling resistance against predominant races. Zak has high-level seedling resistance that is no longer effective against new races. The Yr5 and Yr15 NILs with the stripe rust resistance gene Yr5 and Yr15, respectively, in the AVS background are resistant to all races of the stripe rust pathogen identified so far in the US. The Yr18 resistance, also in the AVS background, is not race specific and durable. Crosses of Alpowa, Express, IDO377s, and Zak with AVS are used to identify and map genes in these cultivars for stripe rust resistance. Crosses of Alpowa with Express are used to combine genes for HTAP resistance from each of the cultivars to obtain high-level resistance. Crosses of Zak with Alpowa and Express are used to incorporate HTAP resistance into the Zak background. Crosses of Alpowa and Zak with the Yr5, Yr15, and Yr18 NILs are used to incorporate these effective genes for all-stage (seedling) or HTAP resistance into Alpowa and Zak to improve the Alpowa resistance. F3 and BC1 generations have been obtained for these crosses and are currently used in genetic studies and molecular mapping of resistance genes in these cultivars.
We have developed user-friendly markers for the Yr5 gene. These markers are used in MAS to incorporate the Yr5 resistance into commercial cultivars in several breeding programs and used in our program to clone Yr5 for elucidating resistance mechanisms. We also have developed molecular markers for Yr15. Collaborating with the Campbell and Kidwell labs, we are using the markers to determine presence or absence of Yr15 in breeding lines and to combine both Yr5 and Yr15 into elite breeding lines.
Through collaborating with Ed Souza in the University of Idaho, we evaluated a genetic population of recombinant inbred lines developed from a cross between wheat varieties IDO444 and Rio Blanc and identified genes for all-stage (seedling) and HTAP resistance to stripe rust. The resistance genes are potentially new and should be useful for breeding resistance to stripe rust.
Stephens is the major source for durable HTAP resistance that has been used in the breeding programs in the PNW and has started to used in the other regions. We have identified molecular markers for genes conferring the all-stage (seedling) resistance and some of the genes conferring the durable HTAP resistance. To diversify sources of durable resistance used in breeding programs in the PNW and other regions, we have also initiated molecular mapping study on Druchamp that has a higher level of HTAP resistance than Stephens and its HTAP resistance is conferred by different genes.
Wheat is generally resistant to the barley stripe rust pathogen and barley is generally resistant to the wheat stripe rust pathogen. Therefore, wheat can be a great source of resistance to barley stripe rust and vice versa. However, genetic basis of these so-called non-host resistances have not been determined. We have made wheat and barley crosses to genetically characterize the resistances. Based on segregation of F2, F3, and backcross progeny tested with selected races, we found that a single dominant gene in Lemhi wheat confers resistance to barley stripe rust and two genes (one dominant and one recessive) in 'Steptoe' barley conferring resistance to wheat stripe rust. With 11 resistance gene analog polymorphism (RGAP) markers, we mapped the wheat gene on chromosome 1B close to but different from Yr21, previously identified in our lab. A linkage group with 12 RGAP markers was constructed for the dominant gene in Steptoe for resistance to wheat stripe rust. The study provides scientific basis to utilize genes in barley for resistance to races of wheat stripe rust and vice versa.
Constructing hexaploid wheat BAC library for cloning genes for resistance to stripe rust. A genomic BAC library of common wheat has been constructed using the wheat Yr5 line. The BAC library consists of 410,000 clones with an average insert size of 130 kb and covers approximately 3.3x wheat genome equivalents. Colony pools and high-density filters of the BAC library have been made for identifying resistance clones. Molecular markers specific to the Yr5 resistance gene were used to screen the multidimensional BAC clone pools. To isolate the expressed sequences from the candidate regions, a cDNA library from the Yr5 line was constructed and is screened with candidate regions as a probe. The wheat BAC library will be used to clone other genes for stripe rust resistance and study of wheat genomics.
Determining effectiveness and use of foliar fungicides for rust control. Fungicides were evaluated for controlling stripe rust in spring wheat plots near Pullman, WA. Wheat cultivars Zak and Fielder were planted on 27 April, 2003. Eight fungicide treatments were conducted on 2 July at the flowering stage. Plots for untreated checks were not sprayed. A randomized block design was used with four replications for each treatment. Data on stripe rust severity (percent foliage with stripe rust) were recorded on 2 July before fungicide application and on 17 July at late milk stage. Yields were determined from plots harvested in 18 August. All the fungicide treatments effectively reduced stripe rust severity. All treatment except Quadris applied at 6.1 fl oz/acre significantly increased grain yield compared to the non-treated check on Fielder; and a new fungicide formulation (A13705 SC 200) applied at the rate of 13.7 fl oz/acre significantly increased grain yield on Zak.
Cultivars with various levels of resistance respond differently to fungicide applications. To determine whether it is worthy to apply fungicides on various cultivars, 23 winter wheat and 16 spring wheat cultivars grown in the western U.S. that had not been previously tested for fungicide control were tested in randomized split-block experiments with four replicates near Pullman, WA, in 2003. When highly susceptible cultivars had 10 % stripe rust, a half of a plot was sprayed with Quadris and the other half was not sprayed. Without fungicide application, seven moderately susceptible and susceptible winter wheat cultivars had yield losses ranging from 14 % to 34 %; nine moderately susceptible and susceptible spring wheat cultivars had yield losses from 11 % to 32 %. Fungicide application increased yields by 16-52 %. Fields of these cultivars should be sprayed with fungicides. Five winter and two spring cultivars with moderate level of resistance had yield losses of 5-12 %. Fungicide spray increased yields by 6-14 %. Fungicide application for these cultivars should be determined based on yield potential in various regions. Eleven winter and five spring wheat cultivars of resistance didn't have significant differences in yield between fungicide treated and non-treated blots. The information is useful for growers to make maximum profit by using fungicides and also reduce unnecessary use of fungicides.
USDA-ARS WESTERN WHEAT QUALITY LABORATORY [p. 277]
E-202 Food Science & Human Nutrition Facility East, Washington State University, Pullman, WA 99164, USA.
Craig F. Morris, A.D. Bettge, D.A. Engle, M.L. Baldridge, R.L. Engle, G.E. King, G.L. Jacobson, A.N. Massa, I. Eujayl, E.P. Fuerst, K.R. Gedye, C.C. Burke, P. Greenwell, H. Tanaka, W.J. Kelley, M.J. Freston, P.K. Boyer, L. Nguyen, E.E. Galli, S.M. Finnie, E. Wagner, S.M. Leach, and Y. Haruta.
The mission of the lab is two-fold: conduct milling, baking, and end-use quality evaluations on wheat breeding lines, and conduct research on wheat grain quality and utilization. The lab continues to move into web-based information transfer and has added extensive enhancements to our web site: http://www.wsu.edu/~wwql/php/index.php. To provide greater access to our research, we developed a database of wheat varieties relating kernel hardness and puroindoline allele. We are in the process of placing our research publications on our web site.
We are serving as curator of the grain hardness, puroindoline, and Gsp-1 gene sections of the Catalogue of Gene Symbols in Wheat. Several new alleles have been documented in Ae. tauschii, synthetic hexaploids from CIMMYT, and other diploid taxa.
We are in the process of establishing the Sino-U.S. Joint Centers for Wheat Quality and Pathology in collaboration with Dr. He, CIMMYT-Beijing, and the Institute of Crop Breeding and Cultivation, Chinese Academy of Agricultural Sciences, USDA-ARS, and Washington State University.
C.F. Morris and D.A. Engle lead the Pacific Northwest Wheat Quality Council, a consortium of collaborators who evaluate the quality of new cultivars and advanced breeding lines.
A.D. Bettge currently serves as chairman of the AACC Soft Wheat and Flour Technical Committee. New methodology for the analysis of end-use characteristics of wheat is studied by this committee for inclusion in the AACCs Approved Methods manual. Recent methods that have been studied collaboratively and approved include, i) Solvent Retention Capacity (SRC), which estimates a number of end-use quality factors such as protein quality, starch damage and pentosan content, and ii) Flour Swelling Volume (FSV), which measures starch swelling and the impact of granule-bound starch synthase allelic state. An L-DOPA substrate-based method for estimation of polyphenol oxidase content of wheat, a contributor to Asian noodle discoloration has been submitted for approval and inclusion in the Approved Methods manual.
C.F. Morris was awarded an OECD fellowship and will spend 6 weeks in the laboratory of Dr. Zoltan Bedö, Agricultural Research Institute of the Hungarian Academy of Sciences, Martonvasar, Hungary.
Postdoctoral research associates include A.N. Massa, I. Eujayl,
E.P. Fuerst, K.R. Gedye, and C.C. Burke; visiting scientists are
P. Greenwell and H. Tanaka; and Y. Haruta is a visitor from a
Japanese milling company.