title: Resin secretory structures of Boswellia papyrifera and implications for frankincense yield.
abstract: OBJECTIVE
  Frankincense, a gum-resin, has been tapped from Boswellia papyrifera trees for centuries. Despite the intensive tapping and economic interest of B. papyrifera, information on the resin secretory structures, which are responsible for synthesis, storage and transport of frankincense, is virtually absent. This study describes the type, architecture and distribution of resin secretory structures of B. papyrifera and its relevance for the ecophysiology and economic use of the tree.
  
  
  METHODS
  The type and architecture of resin secretory structures present in bark and wood was investigated from transversal, tangential and radial sections of bark and wood samples. The diameter and density (number of resin canals mm(-2)) of axial resin canals were determined from digital images of thin sections across the different zones of inner bark.
  
  
  RESULTS
  Resin canals form a three-dimensional network within the inner bark. Yet, the intact resin-conducting and producing network is on average limited to the inner 6·6 mm of the inner bark. Within the inner bark, the density of non-lignified axial resin canals decreases and the density of lignified resin canals increases from the vascular cambium towards the outer bark. In the wood, only radial resin canals were encountered.
  
  
  CONCLUSIONS
  Frankincense tapping techniques can be improved based on knowledge of bark anatomy and distribution and architecture of resin secretory structures. The suggested new techniques will contribute to a more sustainable frankincense production that enhances the contribution of frankincense to rural livelihoods and the national economy.
authors.affiliation: Forest Ecology and Forest Management Group, Wageningen University and Research Centre, PO Box 47, 6700 AA Wageningen, The Netherlands. motuma.feyissa@wur.nl
authors.forename: Motuma
authors.initials: M
authors.lastname: Tolera
authors.forename: David
authors.initials: D
authors.lastname: Menger
authors.forename: Ute
authors.initials: U
authors.lastname: Sass-Klaassen
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Sterck
authors.forename: Paul
authors.initials: P
authors.lastname: Copini
authors.forename: Frans
authors.initials: F
authors.lastname: Bongers
mesh_terms: D029743:Boswellia / Q000033:anatomy & histology* / Q000737:chemistry*; D005002:Ethiopia; D024301:Plant Bark / Q000033:anatomy & histology / Q000737:chemistry; D012116:Resins, Plant / Q000737:chemistry*
chemical_list: D012116:Resins, Plant