Plant Biol (Stuttg) 2005; 7(2): 148-155
DOI: 10.1055/s-2005-837575
Research Paper

Georg Thieme Verlag Stuttgart KG · New York

Cytological Development and Sesquiterpene Lactone Secretion in Capitate Glandular Trichomes of Sunflower

J. C. Göpfert1 , N. Heil1 , J. Conrad2 , O. Spring1
  • 1Institute of Botany, University of Hohenheim, Garbenstraße 30, 70599 Stuttgart, Germany
  • 2Bioorganic Chemistry, University of Hohenheim, Garbenstraße 30, 70599 Stuttgart, Germany
Further Information

Publication History

Received: October 26, 2004

Accepted: January 19, 2005

Publication Date:
11 April 2005 (online)

Abstract

The secretion of sesquiterpene lactones (STL) in capitate glandular trichomes from the anther appendages of Helianthus annuus L. (Asteraceae) was observed by light and fluorescence microscopy and HPLC analysis. Disk flowers within the sunflower capitulum showed the known ontogenetic progression from the centre to the margin. During development of the florets, the trichomes in the anther appendages secreted their metabolites into the subcuticular secretion storage space in front of the two apical cells. All stages of forming the cuticular globe, from the pre-secretory to the post-secretory phase, could be observed microscopically and secretory activity was simultaneously monitored. Six germacrolides and heliangolides of known structure were selected for quantitative analysis. The increase in STL content during extension of the subcuticular space was monitored by HPLC analysis. Thereby, the start and termination of STL biosynthesis was defined in relation to other developmental stages of floret ontogenesis, particularly, the pollen formation. Part of the secreted material showed autofluorescence which could be attributed to a hydroxy-trimethoxy-flavone, as determined by NMR and mass spectroscopy. The anther trichomes were cytologically and chemically similar to foliar glandular trichomes of sunflower and represent the multicellular capitate glandular trichome type common to many Asteraceae. The ease with which anther trichomes of H. annuus can be harvested and analyzed suggests that they can provide a valuable model system for investigation of STL and flavonoid metabolism in Asteraceae.

References

O. Spring

Universität Hohenheim
Institut für Botanik (210)

70593 Stuttgart

Germany

Email: spring@uni-hohenheim.de

Editor: E. Pichersky

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