Left-right leaf asymmetry in decussate and distichous phyllotactic systems.
Leaves in plants with spiral phyllotaxy exhibit directional asymmetries, such that all the leaves originating from a meristem of a particular chirality are similarly asymmetric relative to each other. Models of auxin flux capable of recapitulating spiral phyllotaxis predict handed auxin asymmetries in initiating leaf primordia with empirically verifiable effects on superficially bilaterally symmetric leaves. Here, we extend a similar analysis of leaf asymmetry to decussate and distichous phyllotaxy. We found that our simulation models of these two patterns predicted mirrored asymmetries in auxin distribution in leaf primordia pairs. To empirically verify the morphological consequences of asymmetric auxin distribution, we analysed the morphology of a tomato sister-of-pin-formed1a (sopin1a) mutant, entire-2, in which spiral phyllotaxy consistently transitions to a decussate state. Shifts in the displacement of leaflets on the left and right sides of entire-2 leaf pairs mirror each other, corroborating predicted model results. We then analyse the shape of more than 800 common ivy (Hedera helix) and more than 3000 grapevine (Vitis and Ampelopsis spp.) leaf pairs and find statistical enrichment of predicted mirrored asymmetries. Our results demonstrate that left-right auxin asymmetries in models of decussate and distichous phyllotaxy successfully predict mirrored asymmetric leaf morphologies in superficially symmetric leaves.This article is part of the themed issue 'Provocative questions in left-right asymmetry'.
Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
Ciera C
0000-0003-4296-998X
CC
Martinez
Donald Danforth Plant Science Center, St Louis, MO 63132, USA.
Daniel H
0000-0003-4875-1447
DH
Chitwood
Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Cologne 50829, Germany.|Institute of Plant Sciences, University of Bern, 3013 Bern, Switzerland.
Richard S
RS
Smith
Department of Plant Biology, University of California, Davis, CA 95616, USA nrsinha@ucdavis.edu.
Neelima R
0000-0002-1494-7065
NR
Sinha
D018506:Gene Expression Regulation, Plant; D035981:Hedera / Q000235:genetics / Q000254:growth & development*; D007210:Indoleacetic Acids / Q000378:metabolism; D018551:Solanum lycopersicum / Q000235:genetics / Q000254:growth & development*; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development*; D027844:Vitaceae / Q000235:genetics / Q000254:growth & development*
D007210:Indoleacetic Acids
auxin; leaf development; phyllotaxy; plant development; symmetry