Bearded or Smooth? Awns improve yield when wheat experiences heat stress during grain fill in the southeastern United States

Authors: DEWITT, NOAH - Louisiana State University; LYERLY, JEANETTE - North Carolina State University; GUEDIRA, MOHAMMED - North Carolina State University; Holland, Jim - Jim; MURPHY, J. PAUL - North Carolina State University; WARD, BRIAN - Forage Genetics International; BOYLES, RICHARD - Clemson University; MERGOUM, MOHAMED - University Of Georgia; BABAR, MD ALI - University Of Florida; SHAKIBA, EHSAN - University Of Arkansas; IBRAHIM, AMIR - Texas A&M University; TIWARI, VIJAY - University Of Maryland; SANTANTONIO, NICHOLAS - Virginia Tech; VAN SANFORD, DAVID - University Of Kentucky; HARRISON, STEPHEN - Louisiana State University; Brown-Guedira, Gina

Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/9/2023
Publication Date: 8/21/2023
Citation: Dewitt, N., Lyerly, J., Guedira, M., Holland, J.B., Murphy, J., Ward, B.P., Boyles, R.E., Mergoum, M., Babar, M., Shakiba, E., Ibrahim, A., Tiwari, V., Santantonio, N., Van Sanford, D., Harrison, S.A., Brown Guedira, G.L. 2023. Bearded or Smooth? Awns improve yield when wheat experiences heat stress during grain fill in the southeastern United States. Journal of Experimental Botany. 74(21):6749-6759. https://doi.org/10.1093/jxb/erad318.
DOI: https://doi.org/10.1093/jxb/erad318

Interpretive Summary: The presence or absence of awns – whether a wheat line is ”bearded” or ”smooth” – is the most visible trait distinguishing wheat cultivars. Previous studies suggest that presence of awns may improve yields in heat or water-stressed environments. We used information about presence or absence of awns in wheat breeding lines in combination with grain yield and climate data to estimate the yield effects of awns under different environmental conditions over a 12 year period in the Southeast US. We found that in some environments, absence of awns was associated with higher yields, but presence of awns was associated with better performance in heat-stressed environments more common at southern US locations. Wheat breeders in environments where awns are only beneficial in some years may consider selection for awned lines to reduce year-to-year yield variability, and with an eye towards future climates.

Technical Abstract: The presence or absence of awns – whether a wheat line is ”bearded” or ”smooth” – is the most visible phenotype distinguishing wheat cultivars. Previous studies suggest that awns may improve yields in heat or water-stressed environments, but the exact contribution of awns to yield differences remains unclear. Here we leverage historical phenotypic, genotypic, and climate data to estimate the yield effects of awns under different environmental conditions over a 12 year period in the Southeast US. Lines were classified as awned or awnless based on sequence data, and observed heading dates were used to associate grain fill periods of each line in each environment with climatic data and grain yield. In most environments, awn suppression was associated with higher yields, but awns were associated with better performance in heat-stressed environments more common at southern locations. Wheat breeders in environments where awns are only beneficial in some years may consider selection for awned lines to reduce year-to-year yield variability, and with an eye towards future climates.