DOI: 10.5061/dryad.6nd96
title: Data from: Still armed after domestication? Impact of domestication and agronomic selection on silicon defences in cereals

description: 1. Plant phenotypes reflect trade-offs between competing
 resource-intensive physiological processes. A shift in resource
 allocation, away from anti-herbivore defences and towards growth and
 reproduction, is predicted through plant domestication, such that crops
 are faster growing and higher yielding than their wild ancestors. These
 changes are hypothesized to have come at the cost of defence investment,
 leaving crops ‘disarmed by domestication’. Silicon is the principal
 anti-herbivore defence in grasses, including many of our most important
 staple cereal crops, but the impact of domestication on silicon-based
 defences is unknown. 2. We measured the effects of both domestication and
 modern agronomic selection on growth rate and a suite of anti-herbivore
 defences, specifically leaf toughness, silicon and phenolic
 concentrations. Our comparison of wild, landrace and modern cultivated
 cereals spanned multiple cereal species, including wheat, barley and
 maize, sampling eight independent domestication events and five examples
 of modern agronomic selection. 3. Leaf silicon concentration showed a
 small, but significant, 10% reduction through domestication, but there was
 no effect of modern agronomic selection, and phenolic concentration was
 not affected by either factor. Silicon concentration correlated positively
 with leaf tensile strength, but negatively with foliar phenolic
 concentrations, suggesting a trade-off between chemical and physical
 defences. Size-standardised growth rate was independent of domestication
 status, and did not trade-off with silicon or phenolic defences. However,
 modeling showed that relative growth rate slowed more with increasing size
 in plants with higher silicon levels, so that they reached a smaller final
 size, implying a cost of silicon-based defence. We found the opposite
 pattern for phenolic-based defence, with increasing phenolic
 concentrations associated with a greater plant size at maturity, and
 faster maximum relative growth rates. 4. Silicon-based defences have been
 reduced in cereals through domestication, consistent with our predicted
 costs of these defences to growth. However, modern agronomic selection has
 not influenced silicon defences in cereal crops and the small decrease in
 silicon concentration associated with domestication is unlikely to have a
 major effect on the ability of cereals to withstand a range of abiotic and
 biotic stresses. These findings have broad implications for crop
 protection and our understanding of plant trade-offs.
description: Individual level defence
 dataIndividual level values
 of foliar silicon concentration (% dry mass), tensile strength (N mm-1)
 and phenolic concentration (% DM) for 21 cereal species. Domestication
 status ("Status" column) is indicated as W (wild ancestor), L
 (landrace) or C (modern cultivar)Defence
 data.csvGrowth rate
 dataPlant mass data from
 destructive harvests for 21 cereal species over 30 days. Domestication
 status ("Status" column) is indicated by W (wild ancestor), L
 (landrace) or C (modern cultivar). All units are given in column
 names.