Interacting effects of crop domestication and soil resources on leaf and root functional traits

Domestication altered wheat leaf functional trait expression, and soil amendments altered root trait expression. These alterations shape crop suitability to stressed environments, and informs variety selection for agronomic conditions. Crop traits have been altered through domestication, resulting in syndromes that assist modern crops in contending with environmental constraints. Yet, we have limited understanding of how domestication has shaped the ability of crops to alter leaf and root functional traits for optimal performance under contemporary agronomic conditions, such as water limitation and organic amendments. We used a greenhouse pot experiment that included a wild progenitor of wheat (Aegilops tauschii), three domesticated wheat (Triticum aestivum) varieties (Watkins, Red Fife and Marquis), and three modern wheat varieties (developed from 1969 to 2016) to assess the effects of domestication on crop functional traits under water limitation and under organic and inorganic soil amendments, and to evaluate how this trait expression moderates rhizosphere soil conditions. Leaf functional trait expression varied significantly across wheat domestication classes, with these differences being almost independent of soil amendment or watering treatments. The wild progenitor expressed resource conservative leaf trait values, with low water use efficiency and stomatal conductance. Root trait expression was influenced by both soil amendment and watering treatment, with all wheat lineages expressing acquisitive traits, e.g., higher specific root length and lower root diameter, under organic amendments. Soil amendments and watering treatments impacted rhizosphere conditions, including microbial diversity and acid phosphatase activity, and domestication class impacted fungal diversity. Broadly, domestication altered the expression of wheat leaf functional traits, and soil amendments altered the expression of wheat root functional traits. These alterations in trait expression and rhizosphere soil response shape crop suitability to drought-prone or nutrient stressed environments, and should be considered when selecting varieties for hybridization for contemporary agronomic conditions.