Data from: Leaf shape in Populus tremula is a complex, omnigenic trait.

Leaf shape is a defining feature of how we recognise and classify plant
species. Although there is extensive variation in leaf shape within many
species, few studies have disentangled the underlying genetic
architecture. We characterised the genetic architecture of leaf shape
variation in Eurasian aspen (Populus tremula L.) by performing a genome
wide association studies (GWAS) for physiognomy traits. To ascertain the
roles of identified GWAS candidate genes within the leaf development
transcriptional program, we performed gene co-expression network analyses
from a developmental series, which is publicly available within the
PlantGenIE resource. We additionally used gene expression measurements
across the population to analyse GWAS candidate genes in the context of a
population-wide co-expression network and to identify genes that were
differentially expressed between groups of individuals with contrasting
leaf shapes. These data were integrated with expression GWAS (eQTL)
results to define a set of candidate genes associated with leaf shape
variation. Our results identified no clear adaptive link to leaf shape
variation and indicate that leaf shape traits are genetically complex,
likely determined by numerous small-effect variations in gene expression.
Genes associated with shape variation were peripheral within the
population-wide co-expression network, were not highly connected within
the leaf development co-expression network and exhibited signatures of
relaxed selection. As such, our results are consistent with the omnigenic
model.