Genetic Improvement of Winter Wheat for End-Use Quality and Disease Resistance
Grain, Forage & Bioenergy Research
Project Number: 5440-21000-031-00
Start Date: Oct 29, 2013
End Date: Sep 30, 2018
Objective 1: Identify and develop winter wheat germplasm having novel quality traits, including modified starch composition, enhanced gluten strength, reduced levels of grain polyphenol oxidase, and enhanced mineral element concentration. [NP301, C1, PS1A]
• 1.A. Identify waxy wheats with grain yield equal in magnitude and stability to that of current wheat cultivars.
• 1.B. Develop new waxy wheat breeding lines for germplasm and cultivar release.
• Sub-objective 1.C. Determine the factors governing the efficiency of gluten extraction from waxy wheats.
• 1.D. Develop winter wheats with elevated grain protein content and elevated Fe, Zn and available P concentrations via genetics and breeding.
• 1.E. Determine the relationship between super-low (nil) grain polyphenol oxidase (PPO) and product quality; determine the environmental stability of the nil PPO trait.
• 1.F. Develop adapted hard white winter wheat germplasm with nil levels of grain PPO.
Objective 2: Characterize existing wheat genes conferring virus resistance, identify new sources of resistance to Wheat streak mosaic and Triticum mosaic virus, and pyramid these traits with genes conditioning resistance to wheat stem rust and pre-harvest sprouting. [NP301, C1, PS1A; NP 303, C3, PS3A].
• 2.A. Elucidate the underlying mechanism of virus resistance in the resistant wheat variety Mace, its derivatives, and other sources to identify new disease-resistant lines with increased yield potential
• 2.B. Develop and evaluate transgenic wheat for disease resistance by expression of viral genome sequences in various forms
• 2.C. Pyramid genes for resistance to stem rust and Wheat streak mosaic virus with genes conditioning quality traits, including nil PPO and tolerance to pre-harvest sprouting.
• 2.D. Identify, evaluate and exploit sources of tolerance to pre-harvest sprouting.
• 2.E. Coordinate the Hard Winter Wheat Regional Nursery Program and use the nurseries to: 1) determine the yield potential and stability of newly developed hard winter wheat germplasm, and 2) distribute germplasm to Great Plains breeding programs.
Objective 3: Characterize Triticum mosaic virus and Wheat streak mosaic virus in terms of gene function and rate of molecular evolution. [NP303, C2, PS2A].
• 3.A. Define the role of Triticum mosaic virus proteins in semi-persistent transmission by the wheat curl mite, vector of both Wheat streak mosaic virus and Triticum mosaic virus.
• 3.B. Identify and characterize Triticum mosaic virus gene functions, host interactions and rate of evolution, and strain differentiation during horizontal transmission.
The project will combine classical breeding with the modern genetic tools of transformation and DNA marker technology to develop wheat germplasm and cultivars with traits of economic importance. Multi-location field trials will be used to assess the stability of advanced waxy wheat breeding lines relative to those of the most commonly grown current NE and SD cultivars. The project also will expand the selection of waxy wheat cultivars via breeding and selection. Cereal chemistry techniques will be used to determine the relationships between gluten extraction of waxy wheat and easily scored classical indicators of gluten strength, the mixograph, and high-molecular-weight (HMW) glutenin composition. Recombinant inbred lines will be used to determine whether, in the presence of low phytate mutants, the high protein gene GPC-B1 can be used to simultaneously elevate grain protein, Fe and Zn concentrations, and whether such effects result in pleiotropic effects on grain yield. This project will alleviate deficiencies in the current hard white wheat gene pool by developing wheats with low levels of grain polyphenol oxidase, tolerance to pre-harvest sprouting, and resistance to wheat stem rust and Wheat streak mosaic (WSMV) and Triticum mosaic (TriMV) viruses. Genes for these traits will be pyramided using traditional mating approaches, and fixed in resultant germplasm via direct phenotypic selection, and DNA marker evaluations.
Virtually nothing is known about the molecular biology of TriMV and the roles of viral proteins in replication, vector transmission, and virus-plant host interactions. Improved understanding of the genetic basis of these basic viral functions will be gained by characterization of induced mutants in viral genes. Antibody and nucleic acid based approaches will be used to develop novel procedures to study viral replication and transmission. The mechanism of resistance present in wheat lines carrying known resistance genes Wsm-1 (effective against both WSMV and TriMV) and Wsm-2 will be investigated via characterization of small interfering (si)RNAs produced by resistant plants. Knowledge gained from these experiments will be used to develop transgenic wheat with resistance likely to be effective against a broad spectrum of WSMV and TriMV strains.