Figure 4.

Confocal laser scanning microscopy of translocating SEs in intact V. faba (A), S. lycopersicum (B), C. pepo (C), and O. basilicum (D) plants. CFDA was applied to an apical transport window in the main leaf vein. Within a time range of 30 to 120 min depending on the distance to the observation window and on the plant species, fluorochrome translocation (green) through intact sieve tubes was observed. CFDA fluorescence is restricted to the SE/CCs, indicative of a symplasmic disjunction between SE/CCs and PPCs in transport phloem of the plant species tested. Double staining by fluorescent RH414 applied to the window at the site of observation provided a better demarcation of SEs and CCs (Knoblauch and van Bel, 1998).