Evolutionary Developmental Biology (Evo-Devo)
Plant , Alastair Robert , Bhattacharya, Anandi , Scholz, Andrea , Gleissberg, Stefan .
Conservation of dissected leaf ontogenetic regulation between basal and core eudicots.
Leaves share a common basic developmental program, yet the gross morphology of leaves is highly variable. In dissected leaves, number, arrangement and the direction of initiation of marginal structures is diverse among taxa, likely reflecting modifications of the temporal-spatial interplay of processes maintaining morphogenesis on the one hand, and promoting histogenesis and maturation on the other. In the basal eudicot family Papaveraceae, diverse modes of leaflet initiation and leaf architectures have evolved. We explore the role of a promoter of leaf maturation, CINCINNATA (CIN) in leaf development of Eschscholzia californica, the California poppy, using functional and gene expression studies. Eschscholzia californica CINCINNATA (EcCIN) is homologous to the Antirrhinum majus gene CINCINNATA, the Arabidopsis thaliana TCP 4, and the Solanum lycopersicum LANCEOLATE. In these core eudicots, CIN-like genes negatively regulate cell proliferation and promote a basipetally progressing wave of leaf maturation. In Solanum mutants overexpressing LANCEOLATE, precocious loss of marginal morphogenetic competence effectively eliminates leaflet initiation. To date, no other functional studies are available on the role of CIN genes in dissected leaf development. Downregulation of EcCIN by virus-induced gene silencing (VIGS) with constructs containing different fragments of the target gene strongly increases the number of leaflets formed in Eschscholzia leaves. Increased dissection is not uniform throughout the leaf, but concentrated in proximal parts of the leaf blade. In situ hybridization of EcCIN mRNA indicates that expression is restricted to older, maturing leaf primordia with gradual restriction to leaflets. Unlike in Antirrhinum, a floral phenotype is not observed. We propose that the role of CIN genes in antagonizing leaflet production by promoting maturation is conserved between Eschscholzia and the core eudicot Solanum, but in Eschscholzia is restricted to formation of higher order leaflets in proximal leaf parts later in morphogenesis. We also report on ongoing experiments to characterize the roleof Eschscholzia californica PHANTASTICA (EcPHAN), a MYB domain gene that in core eudicots is involvedin adaxial-abaxial polarityspecification and repression of Class I KNOX genes, and that is negatively regulated by the CIN gene TCP4 in Arabidopsis. VIGS-mediated silencing of EcPHAN using a MYB domain specific construct did not cause abnormal leaf phenotypes despite expression of EcPHAN in the adaxial domains of wild-type leaf primordia; however, induction of additional petalloid lamina flapson the adaxial surface of petals and trumpet-shaped petals were observed, suggesting a specific role of EcPHAN in petal polarity.
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Gleissberg Lab Research Pages
1 - Ohio University, Environmental and Plant Biology, Porter Hall, Richland Avenue, Athens, OH, 45701, USA
2 - Environmental And Plant Biology, 424 Yonge Street, Suite 1016, Toronto, ON, M5B2H3, Canada
Presentation Type: Poster:Posters for Topics
Location: Battelle South/Convention Center
Date: Monday, July 9th, 2012
Time: 5:30 PM