K. Soumelidou et al., THE EFFECT OF AUXIN AND CALCIUM-ANTAGONISTS ON TRACHEARY ELEMENT DIFFERENTIATION IN PHASEOLUS-VULGARIS L, Journal of plant physiology, 143(6), 1994, pp. 717-721
Auxin induced the formation of tracheary elements in bean seedlings wh
en applied for 24 h to a point source in the hypocotyl. Differentiated
tracheary elements appeared basipetally to the application point. Ver
apamil, a Ca2+ channel blocker, and LiCl, a reported inhibitor of Ca2 release from intracellular stores, both inhibited tracheary element d
ifferentiation when applied after auxin. However La3+, an inhibitor of
Ca2+ uptake, was without effect on auxin-induced tracheary element di
fferentiation. The results are discussed in relation to xylogenesis in
tissue culture, which requires Ca2+, and vascular strand formation in
whole plants, which requires polar auxin transport. It is concluded t
hat Ca2+ is necessary for auxin-induced vascular strand differentiatio
n in the intact plant.