title: Periodic root branching in Arabidopsis requires synthesis of an uncharacterized carotenoid derivative.
abstract: In plants, continuous formation of lateral roots (LRs) facilitates efficient exploration of the soil environment. Roots can maximize developmental capacity in variable environmental conditions through establishment of sites competent to form LRs. This LR prepattern is established by a periodic oscillation in gene expression near the root tip. The spatial distribution of competent (prebranch) sites results from the interplay between this periodic process and primary root growth; yet, much about this oscillatory process and the formation of prebranch sites remains unknown. We find that disruption of carotenoid biosynthesis results in seedlings with very few LRs. Carotenoids are further required for the output of the LR clock because inhibition of carotenoid synthesis also results in fewer sites competent to form LRs. Genetic analyses and a carotenoid cleavage inhibitor indicate that an apocarotenoid, distinct from abscisic acid or strigolactone, is specifically required for LR formation. Expression of a key carotenoid biosynthesis gene occurs in a spatially specific pattern along the root's axis, suggesting spatial regulation of carotenoid synthesis. These results indicate that developmental prepatterning of LRs requires an uncharacterized carotenoid-derived molecule. We propose that this molecule functions non-cell-autonomously in establishment of the LR prepattern.
authors.affiliation: Department of Biology, Duke Center for Systems Biology and Howard Hughes Medical Institute, Duke University, Durham, NC 27708.
authors.forename: Jaimie M
authors.initials: JM
authors.lastname: Van Norman
authors.forename: Jingyuan
authors.initials: J
authors.lastname: Zhang
authors.forename: Christopher I
authors.initials: CI
authors.lastname: Cazzonelli
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Pogson
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Harrison
authors.forename: Timothy D H
authors.initials: TD
authors.lastname: Bugg
authors.forename: Kai Xun
authors.initials: KX
authors.lastname: Chan
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Thompson
authors.forename: Philip N
authors.initials: PN
authors.lastname: Benfey
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001681:Biological Assay; D053898:Biosynthetic Pathways / Q000187:drug effects; D002338:Carotenoids / Q000096:biosynthesis*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics; D007783:Lactones / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D019207:beta Carotene / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D007783:Lactones; D019207:beta Carotene; D002338:Carotenoids; D000040:Abscisic Acid; D008156:Luciferases
keywords: patterning; root development; secondary metabolite synthesis