Invited Presenter

Moshood Agba Bakare ¹, Felipe Sabadin ², Amelia Loeb ¹, Alexis Perry ¹, Sunilda Frias ¹, Limei Liu ¹, Wynse Brooks ¹, Noah Dewitt ³, Gina Brown-Guidera ⁴, Nicholas Santantonio ¹
1. School of Plant and Environmental Sciences, Virginia Tech, Blacksburg VA 24060
2. Department of Plants, Soil, and Climate, Utah State University, Logan, UT 84322
3. School of Plant, Environmental and Soil Sciences, Louisiana State University Ag Center, Baton Rouge, LA, 70803
4. USDA-ARS Eastern Regional Small Grains Genotyping Lab, Raleigh, NC 27695
Corresponding author: Nicholas Santantonio, nsant@vt.edu

Bakare, Moshood

mab658@vt.edu

Fusarium head blight(FHB) infection occurs at anthesis in wheat (Triticum aestivum L.) and is influenced by weather conditions in and around flowering. Timing of flowering relative to weather conditions causes inherent genotype-by-environment interactions, making it difficult to select for resistant varieties. Understanding which loci contribute toward stable resistance across environmental conditions versus those that are sensitive to weather is critical for improving quantitative resistance to FHB. This study evaluated 879 genotyped lines in misted FHB-inoculated nurseries in Warsaw, Virginia, over four cropping seasons (2019-2022). Here, we present a phenological model of host response to disease infection and progression under variable weather conditions relative to flowering. Weather covariates, including temperature, precipitation, and humidity, were adjusted by the flowering date of each plot, such that weather variables were indicative of conditions at flowering and at one-day intervals for 7 days before and after flowering. Main genetic effects of markers, phenologically adjusted weather variables, and their interactions were included in a Bayesian mixed model to separate the effects into three categories: 1) stable genetic marker effects across environmental conditions, 2) effects of weather on infection and disease progression per se, and 3) unstable genetic effects sensitive to weather conditions, respectively. The deviance information criterion statistic found the phenological model that included all three terms the best for three FHB traits, indicating marker-by-weather interactions were significant. High temperatures at post-anthesis have the greatest effect, reducing the rate and severity of FHB infection and deoxynivalenol (DON) accumulation. Total precipitation had little effect on FHB infection in the misted nursery, but it is likely to have an effect under standard growing conditions. We recommend breeders focus on stable genetic effects on host resistance and explicitly ignore or select against those with unstable effects.

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