title: The making of a compound inflorescence in tomato and related nightshades.
abstract: Variation in the branching of plant inflorescences determines flower number and, consequently, reproductive success and crop yield. Nightshade (Solanaceae) species are models for a widespread, yet poorly understood, program of eudicot growth, where short side branches are initiated upon floral termination. This "sympodial" program produces the few-flowered tomato inflorescence, but the classical mutants compound inflorescence (s) and anantha (an) are highly branched, and s bears hundreds of flowers. Here we show that S and AN, which encode a homeobox transcription factor and an F-box protein, respectively, control inflorescence architecture by promoting successive stages in the progression of an inflorescence meristem to floral specification. S and AN are sequentially expressed during this gradual phase transition, and the loss of either gene delays flower formation, resulting in additional branching. Independently arisen alleles of s account for inflorescence variation among domesticated tomatoes, and an stimulates branching in pepper plants that normally have solitary flowers. Our results suggest that variation of Solanaceae inflorescences is modulated through temporal changes in the acquisition of floral fate, providing a flexible evolutionary mechanism to elaborate sympodial inflorescence shoots.
authors.affiliation: The Hebrew University of Jerusalem Faculty of Agriculture, Institute of Plant Sciences, Rehovot, Israel.
authors.forename: Zachary B
authors.initials: ZB
authors.lastname: Lippman
authors.forename: Oded
authors.initials: O
authors.lastname: Cohen
authors.forename: John P
authors.initials: JP
authors.lastname: Alvarez
authors.forename: Mohamad
authors.initials: M
authors.lastname: Abu-Abied
authors.forename: Irena
authors.initials: I
authors.lastname: Pekker
authors.forename: Ilan
authors.initials: I
authors.lastname: Paran
authors.forename: Yuval
authors.initials: Y
authors.lastname: Eshed
authors.forename: Dani
authors.initials: D
authors.lastname: Zamir
mesh_terms: D000483:Alleles; D018076:DNA, Complementary; D035264:Flowers / Q000235:genetics* / Q000254:growth & development*; D015870:Gene Expression; D005801:Genes, Homeobox; D017343:Genes, Plant; D018551:Solanum lycopersicum / Q000235:genetics / Q000254:growth & development; D018519:Meristem / Q000235:genetics / Q000254:growth & development; D009154:Mutation; D010641:Phenotype; D032322:Solanum / Q000235:genetics* / Q000254:growth & development; D014157:Transcription Factors / Q000235:genetics
chemical_list: D018076:DNA, Complementary; D014157:Transcription Factors