Résumé
1. Human selection, changes in environmental conditions and management
practices drove the phenotypic trajectory of crops during domestication.
The characterization of the crop domestication syndrome lies mostly on
reproductive characters. However, biophysical and ecophysiological
constraints during vegetative growth are also at play and can strongly
impact crop phenotypes. It has been argued that a broadened examination of
crop phenotypes through a functional trait-based lens should improve our
understanding of the domestication syndrome. 2. We used a collection of 39
genotypes representative of key steps during tetraploid wheat
domestication, and grew them in a common garden experiment. We quantified
the vegetative phenotype of each genotype through the measurements of 13
functional traits related to root, leaf and whole-plant dimensions. 3. In
modern cultivars, compared to ancestral forms, leaf longevity was shorter
while net photosynthetic rate, leaf production rate and nitrogen content
were higher. Modern cultivars had a shallower root system and exhibited a
larger proportion of fine roots, preferring to invest biomass above rather
than below ground. We found ancestral forms to be integrated phenotypes
characterized by coordination between above- and below-ground functioning.
Conversely, in modern forms, human selection appeared to have broken this
coordination and to have generated a new type of network of trait
covariations. 4. Synthesis and applications. The examination of leaf,
root, and whole-plant traits of wheat accessions indicated a strong shift
in plant functional strategies over the course of domestication. Elite
genotypes tended to better optimize resource-use acquisition strategies
than ancestral ones. The characterization of the crop phenotype based on
vegetative traits thus suggests a much more complete domestication
syndrome. Our findings highlight the benefits of using a functional
trait-based characterization of crop phenotypes to document the extent of
domestication syndrome and to further advance the agroecological
management of cereals.10-Oct-2017