Arabidopsis thaliana leaf form evolved via loss of KNOX expression in leaves in association with a selective sweep.
Morphological diversity is often caused by altered gene expression of key developmental regulators. However, the precise developmental trajectories through which morphologies evolved remain poorly understood. It is also unclear to what degree genetic changes contributing to morphological divergence were fixed by natural selection. Here we investigate these problems in the context of evolutionary developmental transitions that produced the simple unlobed leaf of the model species Arabidopsis thaliana. We demonstrate that A. thaliana leaf shape likely derived from a more complex lobed ancestral state that persists in extant Arabidopsis species. We also show that evolution of the unlobed leaf form in A. thaliana involved loss of expression of the knotted1-like homeobox gene SHOOTMERISTEMLESS (STM) in leaves and that cis-regulatory divergence contributed to this process. Further, we provide evidence for a selective sweep at the A. thaliana STM locus, indicating that loss of STM expression in A. thaliana leaves may have been fixed by positive selection. In summary, our data provide key information as to when and how the characteristic leaf form of A. thaliana evolved.
Plant Sciences Department, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
Paolo
P
Piazza
C Donovan
CD
Bailey
Maria
M
Cartolano
Jonathan
J
Krieger
Jun
J
Cao
Stephan
S
Ossowski
Korbinian
K
Schneeberger
Fei
F
He
Juliette
J
de Meaux
Neil
N
Hall
Norman
N
Macleod
Dmitry
D
Filatov
Angela
A
Hay
Miltos
M
Tsiantis
D017360:Arabidopsis / Q000033:anatomy & histology* / Q000145:classification / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D005075:Biological Evolution; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010641:Phenotype; D010802:Phylogeny; D018515:Plant Leaves / Q000033:anatomy & histology* / Q000502:physiology*; D012641:Selection, Genetic
D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; C092212:KNAT1 protein, Arabidopsis; C097496:STM protein, Arabidopsis