Data from: Natural variation in GL1 and its effects on trichome density in Arabidopsis thaliana

The ultimate understanding of how biological diversity arises, is
maintained, and lost depends on identifying the genes responsible.
Although a good deal has been discovered about gene function over the past
few decades, far less is understood about gene effects; i.e., how natural
variation in a gene contributes to natural variation in phenotypes.
Trichome density in Arabidopsis thaliana is an ideal trait for studies of
natural molecular and phenotypic variation, as trichome initiation is
genetically well-characterised and trichome density is highly variable in
and among natural populations. Here, we show that variation at GLABRA1
(GL1), an R2R3 MYB transcription factor gene, which has a role in trichome
initiation, has qualitative and likely quantitative effects on trichome
density in natural accessions of A. thaliana. Specifically, we
characterize four independent loss-of-function alleles for GL1, each of
which yields a glabrous phenotype. Further, we find that a pattern of
common polymorphisms confined to the GL1 locus is associated with
quantitative variation for trichome density. While mutations resulting in
a glabrous phenotype are primarily coding changes, the pattern resulting
in quantitative variation spans both coding and regulatory regions. These
data show that GL1 is an important source of trichome density variation
within A. thaliana and, along with recent reports, suggest that the TTG1
epidermal cell fate pathway generally may be the key molecular genetic
source of natural trichome density variation and an important model for
the study of molecular evolution.