title: A staining protocol for identifying secondary compounds in Myrtaceae.
abstract: OBJECTIVE
  Here we propose a staining protocol using toluidine blue (TBO) and ruthenium red to reliably identify secondary compounds in the leaves of some species of Myrtaceae. •
  
  
  RESULTS
  Leaves of 10 species representing 10 different genera of Myrtaceae were processed and stained using five different combinations of ruthenium red and TBO. Optimal staining conditions were determined as 1 min of ruthenium red (0.05% aqueous) and 45 s of TBO (0.1% aqueous). Secondary compounds clearly identified under this treatment include mucilage in the mesophyll, polyphenols in the cuticle, lignin in fibers and xylem, tannins and carboxylated polysaccharides in the epidermis, and pectic substances in the primary cell walls. •
  
  
  CONCLUSIONS
  Potential applications of this protocol include systematic, phytochemical, and ecological investigations in Myrtaceae. It might be applicable to other plant families rich in secondary compounds and could be used as a preliminary screening method for extraction of these elements.
authors.affiliation: School of Earth, Environmental, and Biological Sciences, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4001 Australia.
authors.forename: Hernan A
authors.initials: HA
authors.lastname: Retamales
authors.affiliation: School of Earth, Environmental, and Biological Sciences, Queensland University of Technology, 2 George Street, Brisbane, Queensland 4001 Australia.
authors.forename: Tanya
authors.initials: T
authors.lastname: Scharaschkin
keywords: Myrtaceae; anatomy; ruthenium red; staining; toluidine blue