The NAC-domain transcription factor GOBLET specifies leaflet boundaries in compound tomato leaves

Yael Berger, Smadar Harpaz-Saad, Arnon Brand, Hadas Melnik, Neti Sirding, John Paul Alvarez, Michael Zinder, Alon Samach, Yuval Eshed, Naomi Ori*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

242 Scopus citations

Abstract

Leaves are formed at the flanks of the shoot apical meristem (SAM) and develop into a variety of forms. In tomato, prolonged leaf patterning enables the elaboration of compound leaves by reiterative initiation of leaflets with lobed margins. In goblet (gob) loss-of-function mutants, primary leaflets are often fused, secondary leaflets and marginal serrations are absent, and SAMs often terminate precociously. We show that GOB encodes a NAC-domain transcription factor expressed in narrow stripes at the leaf margins, flanking the distal side of future leaflet primordia, and at the boundaries between the SAM and leaf primordia. Leaf-specific overexpression of the microRNA miR164, a negative regulator of GOB-like genes, also leads to loss of secondary-leaflet initiation and to smooth leaflet margins. Plants carrying a dominant gob allele with an intact ORF but disrupted miR164 binding site produce more cotyledons and floral organs, have split SAMs and, surprisingly, simpler leaves. Overexpression of a form of GOB with an altered miR164 binding site in leaf primordia leads to delayed leaflet maturation, frequent, improperly timed and spaced initiation events, and a simple mature leaflet form owing to secondary-leaflet fusion. miR164 also affects leaflet separation in Cardamine hirsuta, a Brassicaceae species with complex leaves. Genetic and molecular analyses suggest that GOB expression is intact in the simplified leaves of entire tomato mutants, which have a defect in a putative repressor of auxin responses. Our results show that GOB marks leaflet boundaries and that its accurate spatial, temporal and quantitative activity affects leaf elaboration in a context-dependent manner.

Original languageAmerican English
Pages (from-to)823-832
Number of pages10
JournalJournal of Embryology and Experimental Morphology
Volume136
Issue number5
DOIs
StatePublished - 1 Mar 2009

Keywords

  • Boundary
  • CUC2
  • Compound leaves
  • MiR164
  • NAM
  • Tomato

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