Breeding soft-seeded hairy vetch

Authors: Riday, Heathcliffe; Tilhou, Neal; Kissing Kucek, Lisa; ALI, SHAJAHAN - Oak Ridge Institute For Science And Education (ORISE); CARR, BRANDON - Natural Resources Conservation Service (NRCS, USDA); YOUNG-MATHEWS, ANNIE - Natural Resources Conservation Service (NRCS, USDA); DOUGLAS, JOEL - Natural Resources Conservation Service (NRCS, USDA); BHAMIDIMARRI, SURESH - Corteva Agriscience; Azevedo, Mark; KROGMAN, SARAH - University Of Kansas; MONTEROS, MARIA - Bayer Cropscience; Mirsky, Steven; Hayes, Ryan; ENGLERT, JOHN - Natural Resources Conservation Service (NRCS, USDA)

Submitted to: Eucarpia Fodder Crops and Amenity Grasses Section Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 9/10/2023
Publication Date: 9/12/2023
Citation: Riday, H., Tilhou, N.W., Kucek, L.K., Ali, S., Carr, B., Young-Mathews, A., Douglas, J., Bhamidimarri, S., Azevedo, M.D., Krogman, S., Monteros, M., Mirsky, S.B., Hayes, R.J., Englert, J. 2023. Breeding soft-seeded hairy vetch. Eucarpia Fodder Crops and Amenity Grasses Section Symposium. September 10-14, 2023.

Interpretive Summary:

Technical Abstract: Hairy vetch (Vicia villosa Roth.) is a major global legume cover crop. Hairy vetch has good survival and excellent spring biomass production. One weakness of hairy vetch is that it has a high incidence of physiological seed dormancy (PY), also known as hard seed. Overcoming this weakness by developing soft seeded varieties would result in greater adoption of hairy vetch in cover crop systems because producers would not have to worry about hairy vetch becoming a weed issue in the seed bank. We report here on progress made in developing soft seeded hairy vetch varieties. A recurrent phenotypic selection program was initiated to develop soft seeded hairy vetch populations. As expected, PY was very dependent on seed production environment. Despite this variability, genetic variation for the trait was determined with an estimated narrow sense heritability estimated at h^2 = 0.40 (Kucek et al., 2020). After two years of selection, soft seeded lines have improved from 74% PY to 67% hard seed, with the most advanced soft-seeded synthetic at 61% PY. We used a genome wide association (GWAS) approach to determine if we could find genomic regions or loci associated with PY. Our intent is that markers associated with PY loci could be used in marker assisted selection (MAS) to accelerate selection gains. As part of the GWAS effort, the first hairy vetch reference assembly was created (Fuller et al., 2023). To generate phenotypic data, in autumn of 2018, two space-plant seed production nurseries were established in Knox City, TX, USA and Corvallis, OR, USA. At each site, 800 seed from 40 half-sibling families were planted for a total of 1600 plants. During the 2019 growing season, plants were allowed to go to flower and produce seed. Ripe unopened seed pods were collected from each plant. Pods were gently opened without disturbing the seed coat of seed within. Germination tests were conducted on processed seed from each plant. Genomic DNA was extracted from each plant followed by Illumina sequencing. SNP GWAS analysis revealed a highly significant association peak (LOD 15) and a secondary smaller peak (LOD 12). The major locus had a 23% PY marker effect per allele dose. This result somewhat confirmed our hypothesis that the trait is controlled by a few major genes and/or genomic regions. Based on these results we are currently developing targeted markers for these two genomic regions for use in MAS schemes.