title: A sister of PIN1 gene in tomato (Solanum lycopersicum) defines leaf and flower organ initiation patterns by maintaining epidermal auxin flux.
abstract: The spatiotemporal localization of the plant hormone auxin acts as a positional cue during early leaf and flower organogenesis. One of the main contributors to auxin localization is the auxin efflux carrier PIN-FORMED1 (PIN1). Phylogenetic analysis has revealed that PIN1 genes are split into two sister clades; PIN1 and the relatively uncharacterized Sister-Of-PIN1 (SoPIN1). In this paper we identify entire-2 as a loss-of-function SlSoPIN1a (Solyc10g078370) mutant in Solanum lycopersicum. The entire-2 plants are unable to specify proper leaf initiation leading to a frequent switch from the wild type spiral phyllotactic pattern to distichous and decussate patterns. Leaves in entire-2 are large and less complex and the leaflets display spatial deformities in lamina expansion, vascular development, and margin specification. During sympodial growth in entire-2 the specification of organ position and identity is greatly affected resulting in variable branching patterns on the main sympodial and inflorescence axes. To understand how SlSoPIN1a functions in establishing proper auxin maxima we used the auxin signaling reporter DR5: Venus to visualize differences in auxin localization between entire-2 and wild type. DR5: Venus visualization shows a widening of auxin localization which spreads to subepidermal tissue layers during early leaf and flower organogenesis, showing that SoPIN1 functions to focus auxin signaling to the epidermal layer. The striking spatial deformities observed in entire-2 help provide a mechanistic framework for explaining the function of the SoPIN1 clade in S.lycopersicum.
authors.affiliation: Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA, USA.
authors.forename: Ciera C
authors.initials: CC
authors.lastname: Martinez
authors.affiliation: Department of Botany and Plant Sciences, University of California at Riverside, Riverside, CA, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Koenig
authors.affiliation: Donald Danforth Plant Science Center, St. Louis, MO, USA.
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Chitwood
authors.affiliation: Department of Plant Biology, University of California at Davis, Davis, CA, USA. Electronic address: nrsinha@ucdavis.edu.
authors.forename: Neelima R
authors.initials: NR
authors.lastname: Sinha
mesh_terms: D001692:Biological Transport; D018389:Codon, Nonsense; D035264:Flowers / Q000254:growth & development* / Q000378:metabolism; D020440:Gene Duplication; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D056726:Genetic Association Studies; D005816:Genetic Complementation Test; D007210:Indoleacetic Acids / Q000378:metabolism*; D018551:Solanum lycopersicum / Q000235:genetics* / Q000254:growth & development; D018519:Meristem / Q000378:metabolism; D005810:Multigene Family / Q000235:genetics; D009154:Mutation; D000072340:NIMA-Interacting Peptidylprolyl Isomerase / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D038081:Organogenesis / Q000235:genetics; D010802:Phylogeny; D018515:Plant Leaves / Q000254:growth & development* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: D018389:Codon, Nonsense; D007210:Indoleacetic Acids; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D010940:Plant Proteins
keywords: Auxin signaling; Phyllotaxy; Sister-of-PIN1; Tomato; entire-2