title: Auxin involvement in tepal senescence and abscission in Lilium: a tale of two lilies.
abstract: Petal wilting and/or abscission terminates the life of the flower. However, how wilting and abscission are coordinated is not fully understood. There is wide variation in the extent to which petals wilt before abscission, even between cultivars of the same species. For example, tepals of Lilium longiflorum wilt substantially, while those of the closely related Lilium longiflorum×Asiatic hybrid (L.A.) abscise turgid. Furthermore, close comparison of petal death in these two Lilium genotypes shows that there is a dramatic fall in fresh weight/dry weight accompanied by a sharp increase in ion leakage in late senescent L. longiflorum tepals, neither of which occur in Lilium L.A. Despite these differences, a putative abscission zone was identified in both lilies, but while the detachment force was reduced to zero in Lilium L.A., wilting of the fused tepals in L. longiflorum occurred before abscission was complete. Abscission is often negatively regulated by auxin, and the possible role of auxin in regulating tepal abscission relative to wilting was tested in the two lilies. There was a dramatic increase in auxin levels with senescence in L. longiflorum but not in Lilium L.A. Fifty auxin-related genes were expressed in early senescent L. longiflorum tepals including 12 ARF-related genes. In Arabidopsis, several ARF genes are involved in the regulation of abscission. Expression of a homologous transcript to Arabidopsis ARF7/19 was 8-fold higher during senescence in L. longiflorum compared with abscising Lilium L.A., suggesting a conserved role for auxin-regulated abscission in monocotyledonous ethylene-insensitive flowers.
authors.affiliation: Department of Biology, University of Pisa, Via Ghini 5, 56126 Pisa, Italy.
authors.forename: Lara
authors.initials: L
authors.lastname: Lombardi
authors.affiliation: Department of Plant Biology, Faculty of Biology, University of Barcelona, Avinguda Diagonal, 645, 08028 Barcelona, Spain School of Biosciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
authors.forename: Laia
authors.initials: L
authors.lastname: Arrom
authors.affiliation: Department of Biology, University of Pisa, Via Ghini 5, 56126 Pisa, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Mariotti
authors.affiliation: Department of Agriculture, Food and Environment, University of Pisa, Via Mariscoglio 34, 56124 Pisa, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Battelli
authors.affiliation: Department of Agriculture, Food and Environment, University of Pisa, Via Mariscoglio 34, 56124 Pisa, Italy.
authors.forename: Piero
authors.initials: P
authors.lastname: Picciarelli
authors.affiliation: School of Biosciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Kille
authors.affiliation: School of Biological Sciences, Royal Holloway, University of London, Egham Hill, Egham, Surrey TW20 0EX, UK.
authors.forename: Tony
authors.initials: T
authors.lastname: Stead
authors.affiliation: Department of Plant Biology, Faculty of Biology, University of Barcelona, Avinguda Diagonal, 645, 08028 Barcelona, Spain.
authors.forename: Sergi
authors.initials: S
authors.lastname: Munné-Bosch
authors.affiliation: School of Biosciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK rogershj@cf.ac.uk.
authors.forename: Hilary J
authors.initials: HJ
authors.lastname: Rogers
mesh_terms: D000595:Amino Acid Sequence; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism*; D027762:Lilium / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D008969:Molecular Sequence Data; D010937:Plant Growth Regulators / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins; D014157:Transcription Factors
keywords: ARF transcription factors; Abscission zone; IAA; Lilium longiflorum; floral senescence; transcriptome.