PLANT PHYSIOLOGY , Vol 101, Issue 1 187-191, Copyright © 1993 by American Society of Plant Biologists
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ENVIRONMENTAL AND STRESS PHYSIOLOGY |
Stimulation of Callose Synthesis in Vivo Correlates with Changes in Intracellular Distribution of the Callose Synthase Activator [beta]-Furfuryl-[beta]-Glucoside
P. Ohana, M. Benziman and D. P. Delmer
Department of Biological Chemistry (P.O., M.B.) and Department of Botany (D.P.D.), Institute of Life Sciences, The Hebrew University, Jerusalem 91904, Israel
[beta]-Furfuryl-[beta]-glucoside (FG) has been shown to be a specific
endogenous activator of higher plant callose synthase (P. Ohana, D.P.
Delmer, G. Volman, J.C. Steffens, D.E. Matthews, M. Benziman [1992] Plant
Physiol 98: 708-715). Because glycosides such as FG are usually sequestered
in vacuoles, we have proposed that activation of callose synthesis in vivo
may involve a change in the compartmentation of FG and Ca2+, resulting in a
synergistic activation of callose synthase. The use of suspension-cultured
barley (Hordeum bulbosum L.) cells provides evidence that FG is largely
sequestered in the vacuole. Furthermore, conditions that lead to induction
of callose synthesis in vivo correspondingly lead to elevation of the
cytoplasmic concentration of FG. These conditions include the lowering of
cytoplasmic pH or elevation of cytoplasmic Ca2+. Oligogalacturonide
elicitors have also been reported to cause similar changes in cytoplasmic
pH and Ca2+ concentration (Y. Mathieu, A. Kurkdjian, H. Xia, J. Guern, A.
Koller, M.D. Spiro, M. O'Neill, P. Albersheim, A. Darvill [1991] The Plant
Journal 1: 333-343), and such an elicitor also causes an elevation in
cytoplasmic FG coupled with stimulation of callose synthesis. These results
support the concept that a relative redistribution of FG between cytoplasm
and vacuole may be one of the components of the signal transduction pathway
for elicitation of callose synthase in vivo.
