Characterization of Linaria KNOX genes suggests a role in petal-spur development
MetadataShow full item record
AbstractSpurs are tubular outgrowths of perianth organs that have evolved iteratively among angiosperms. They typically contain nectar and often strongly influence pollinator specificity, potentially mediating reproductive isolation. The identification of Antirrhinum majus mutants with ectopic petal spurs suggested that petal-spur development is dependent on the expression of KNOTTED 1-like homeobox (KNOX) genes, which are better known for their role in maintaining the shoot apical meristem. Here, we tested the role of KNOX genes in petal spur development by isolating orthologs of the A. majus KNOX genes Hirzina (AmHirz) and Invaginata (AmIna) from Linaria vulgaris, a related species that differs from A. majus in possessing long, narrow petal spurs. We name these genes LvHirz and LvIna, respectively. Using quantitative reverse-transcription PCR, we show that LvHirz is expressed at high levels in the developing petals and demonstrate that the expression of petal associated KNOX genes is sufficient to induce sac-like outgrowths on petals in a heterologous host. We propose a model in which KNOX gene expression during early petal-spur development promotes and maintains further morphogenetic potential of the petal, as previously described for KNOX gene function in compound leaf development. These data indicate that petal spurs could have evolved by changes in regulatory gene expression that cause rapid and potentially saltational phenotypic modifications. Given the morphological similarity of spur ontogeny in distantly related taxa, changes in KNOX gene expression patterns could be a shared feature of spur development in angiosperms.
CitationBox M., Dodsworth S., Rudall P., Bateman R., Glover B. (2011) 'Characterization of Linaria KNOX genes suggests a role in petal-spur development', The Plant Journal, 68 (4), pp.703-714.
JournalThe Plant Journal
- Flower-specific KNOX phenotype in the orchid Dactylorhiza fuchsii.
- Authors: Box MS, Dodsworth S, Rudall PJ, Bateman RM, Glover BJ
- Issue date: 2012 Aug
- KNOX homeobox genes potentially have similar function in both diploid unicellular and multicellular meristems, but not in haploid meristems.
- Authors: Sano R, Juárez CM, Hass B, Sakakibara K, Ito M, Banks JA, Hasebe M
- Issue date: 2005 Jan-Feb
- Spontaneous mutations in KNOX genes give rise to a novel floral structure in Antirrhinum.
- Authors: Golz JF, Keck EJ, Hudson A
- Issue date: 2002 Apr 2
- Comparative transcriptomics of early petal development across four diverse species of Aquilegia reveal few genes consistently associated with nectar spur development.
- Authors: Ballerini ES, Kramer EM, Hodges SA
- Issue date: 2019 Aug 22
- Petaloidy and petal identity MADS-box genes in the balsaminoid genera Impatiens and Marcgravia.
- Authors: Geuten K, Becker A, Kaufmann K, Caris P, Janssens S, Viaene T, Theissen G, Smets E
- Issue date: 2006 Aug