Ecological genetics of root architecture variation in Arabidopsis thaliana in native and non-native environments
Complex phenotypic characters can vary between native and non-native environments and both due to ecology of the habitats and genetics of seed source populations. In addition to changes in trait means, changes in trait relationships vary across environments and across populations. Novel environments can expose both trait variation as well as genetic variation for plasticity of trait correlations. Important root architectural traits have rarely been examined in this context under field conditions in native and non-native habitats. Here we conducted multiple common gardens in the native range of Arabidopsis thaliana in Europe as well as in the non-native range in North America across two years. In the experiments, six populations were represented by 5-15 maternal lines which each were replicated 20 times at each garden site. Survivorship was assayed during the experiment, and when flowering ceased, all plants were harvested. Roots were excavated intact, cleaned and either scanned or digital images were taken for analyses with WinRhizo software. Companion aboveground vegetative and reproductive traits were measured at the time of harvest.
We detected differences among populations in survivorship in the native range in the field garden sites, and overall survivorship was greater in the non-native habitat than the native garden in 2014. Root architecture differed significantly between native and non-native gardens, and among populations. We detected significant genetic variation for plasticity in root architecture traits, as well as plasticity of trait correlations within the root module and in shoot module. Such genetic variation for plasticity as well as genetic variation for plasticity to multivariate changes in soil environments is critical to our understanding of how populations of weedy annual plants establish in both native and non-native environments. Insights from these investigations can be connected to the broad work on this species on the influence of particular root genes from a molecular genetic perspective on plant phenotypes as well as inform variation in closely related crop species.