Tailed forisomes of Canavalia gladiata: A new model to study Ca 2+-driven protein contractility

W. S. Peters, M. Knoblauch, S. A. Warmann, R. Schnetter, A. Q. Shen, W. F. Pickard

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

• Background and AimsForisomes are Ca2+-dependent contractile protein bodies that form reversible plugs in sieve tubes of faboid legumes. Previous work employed Vicia faba forisomes, a not entirely unproblematic experimental system. The aim of this study was to seek to establish a superior model to study these intriguing actuators. • Methods: Existing isolation procedures were modified to study the exceptionally large, tailed forisomes of Canavalia gladiata by differential interference contrast microscopy in vitro. To analyse contraction/expansion kinetics quantitatively, a geometric model was devised which enabled the computation of time-courses of derived parameters such as forisome volume from simple parameters readily determined on micrographs. • Key Results: Advantages of C. gladiata over previously utilized species include the enormous size of its forisomes (up to 55 μm long), the presence of tails which facilitate micromanipulation of individual forisomes, and the possibility of collecting material repeatedly from these fast-growing vines without sacrificing the plants. The main bodies of isolated Canavalia forisomes were box-shaped with square cross-sections and basically retained this shape in all stages of contraction. Ca 2+-induced a 6-fold volume increase within about 10-15 s; the reverse reaction following Ca2+-depletion proceeded in a fraction of that time. • Conclusions: The sword bean C. gladiata provides a superior experimental system which will prove indispensable in physiological, biophysical, ultrastructural and molecular studies on the unique ATP-independent contractility of forisomes.

Original languageEnglish (US)
Pages (from-to)101-109
Number of pages9
JournalAnnals of Botany
Volume100
Issue number1
DOIs
StatePublished - Jul 2007

Keywords

  • Ca-dependent contractility
  • Canavalia gladiata
  • Contractile protein
  • Contraction kinetics
  • Fabaceae
  • Forisome geometry
  • Phloem transport
  • Sieve element
  • Tailed forisome

ASJC Scopus subject areas

  • Plant Science

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