Genome-wide association mapping in hairy vetch (Vicia villosa) discovers a large effect locus controlling seed dormancy

Authors: Tilhou, Neal; Kissing Kucek, Lisa; CARR, BRANDON - Natural Resources Conservation Service (NRCS, USDA); MARION, ANNIE - Natural Resources Conservation Service (NRCS, USDA); DOUGLAS, JOEL - Natural Resources Conservation Service (NRCS, USDA); ENGLERT, JOHN - Natural Resources Conservation Service (NRCS, USDA); ALI, SHAHJAHAN - US Department Of Agriculture (USDA); Raasch, John; BHAMIDIMARRI, SURESH - Corteva Agriscience; Mirsky, Steven; MONTEROS, MARIA - Bayer Cropscience; KROGMAN, SARAH - University Of Kansas Medical School; Hayes, Ryan; Azevedo, Mark; Riday, Heathcliffe

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/6/2023
Publication Date: 10/24/2023
Citation: Tilhou, N.W., Kucek, L.K., Carr, B., Marion, A., Douglas, J., Englert, J., Ali, S., Raasch, J.A., Bhamidimarri, S., Mirsky, S.B., Monteros, M.J., Krogman, S., Hayes, R.J., Azevedo, M.D., Riday, H. 2023. Genome-wide association mapping in hairy vetch (Vicia villosa) discovers a large effect locus controlling seed dormancy. Frontiers in Plant Science. https://doi.org/10.3389/fpls.2023.1282187.
DOI: https://doi.org/10.3389/fpls.2023.1282187

Interpretive Summary: Cover crops are grown between cash crops to improve soil, water, and air quality. Use of cover crops has increased in recent decades, but remains around 5% of non-alfalfa cropland. Hairy vetch (Vicia villosa) is a promising cover crop, but many farmers do not use hairy vetch because it releases seed early (pod shatter or dehiscence) and has dormant seed. This causes weedy hairy vetch populations in later cash crop fields. Plant breeding can eliminate these traits. This study searched for genetic markers which are linked to dehiscence or dormant seed by evaluating 1,019 hairy vetch individuals for genetic markers and field performance in two field sites (Texas and Oregon). The study found a major genetic marker association with seed dormancy. This strong association can accelerate the creation of low seed dormancy hairy vetch cultivars.

Technical Abstract: Hairy vetch (Vicia villosa Roth), a winter hardy annual legume, is a promising cover crop. To fully leverage its potential, seed production and field performance of V. villosa must be improved to facilitate producer adoption. Two classic domestication traits, seed dormancy (hard seed) and dehiscence (pod shatter), are selection targets in an ongoing breeding program. This study reports a genome-wide association study of 1,019 V. villosa individuals evaluated at two sites (Knox City, Texas and Corvallis, Oregon) for proportion of dormant seed, visual pod dehiscence scores, and two dehiscence surrogate measures (force to dehiscence and pod spiraling score). Trait performance varied between sites, but reliability (equivalent to heritability) across sites was strong (dormant seed proportion: 0.68; dehiscence score: 0.61; spiraling score: 0.42; force to dehiscence: 0.41). A major locus controlling seed dormancy was found (q-value: 1.29 x 10-5; Chromosome 1: Position: 63611165), which can be used by breeding programs to rapidly reduce dormancy in breeding populations. No significant dehiscence score QTL were found, primarily due to the high dehiscence rates in Corvallis, Oregon. Since Oregon is a potentially major V. villosa seed production region, further dehiscence resistance screening is necessary.