Yellow dwarf viruses (YDV), comprising strains of barley yellow dwarf virus (BYDV) and cereal yellow dwarf virus (CYDV), constrain cereal production in the United States by causing yellow dwarf disease (YDD). Five principal B/CYDV strains occur in cereals: BYDV-PAV, -MAV, -RMV, -SGV, and CYDV-RPV. Although YDV has been reported in Nebraska, cultivar-specific responses and field-level strain composition remain poorly characterized. We conducted a two-year (2024-2025), multi-location field study at Mead, Fairbury, and Concord, Nebraska to evaluate 10 widely grown wheat and barley cultivars for YDD incidence, virus strain diversity, and aphid infestation. Across years and locations, YDV infection was higher in wheat (29.73%) than in barley (12.53%). In wheat, cv. SY Monument exhibited the highest YDV incidence (36-92%) and the greatest aphid abundance, whereas cv. Ruth consistently showed the lowest incidence (4-20%) and minimal aphid infestation. In barley, cv. Fortress had the highest infection levels (8-48%) and aphid abundance, while cvs. NB19420 and NB21427 were generally the least infected (0-20% and 4-12%, respectively) and supported the lowest aphid populations. Strain composition differed by crop: wheat infections were dominated by PAV-associated single and mixed infections, whereas barley shifted toward MAV-dominated infections with reduced strain diversity. Aphid abundance was positively associated with YDV infection in wheat and barley. Collectively, these results highlight the interacting roles of host susceptibility, strain diversity, and vector dynamics in shaping YDD epidemiology and support integrated cultivar- and vector-based management strategies.
M. Barman, Nikhitha Gangavarapu, Thomas Wilbur Davis et al.· Plant Disease· 0 citations
Two novel WSS resistance loci were identified on chromosomes 2B and 5A. Characterization of WSS resistance loci will improve breeders’ ability to select to reduce yield loss due to WSS. Wheat stem sawfly (WSS) is a native grass feeding pest of winter wheat (Triticum aestivum L) which is difficult to control since most of its life cycle occurs within the stem of wheat plants. The only well-characterized genetic resistance to WSS is the solid stem locus (Sst1) on chromosome 3B, which exhibits environmental variability. It is critical to identify novel forms of genetic resistance outside of Sst1 to improve the overall resistance of wheat to WSS. In this study, genome-wide association studies (GWAS) were performed on lines in the Colorado State University wheat breeding program grown between 2014 and 2025 field seasons for three traits of interest: heading date (HD), WSS damage in the form of stem cutting (CUT), and stem solidity (SOLID). Significant marker trait associations (MTA) were identified on chromosomes 2B, 2D, 3A, 3B, 5A, and 5D for CUT and 2A, 3B, 4B, and 6A for SOLID. Significant MTA from these GWAS were used to identify beneficial allelic combinations (AC) for WSS resistance. The stem cutting ACs which had the lowest damage estimates were those in which lines possessed the resistant haplotype at every locus assessed (CUT = 2.35, error = 0.21, N = 56). Lines that had all resistant alleles in the stem solidity ACs showed the same superior estimate (SOLID = 14.7, error = 0.78, N = 22). The positive effects of the identified small-effect MTA on CUT and SOLID indicated the importance of including these loci when breeding for WSS resistance.
Mikayla Hammers, Z. Winn, Brian R. Rice et al.· Theoretical and Applied Gene...· 0 citations
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