Reply: Escaping a Low-Security Prison

Plant Physiology: Unveiling the Dark Side of Phloem Translocation

“…Moreover, companion cell expression of different fluorescent proteins showed that almost any protein below 70 kDa and not targeted to membranes will eventually end up in sink tissue [8,10]. While there is still some debate about whether this was due to the overexpression of these proteins [11,12], it seems to be clear that proteins and RNAs from companion cells can end up in the phloem stream by chance. In addition, one should not forget that as part of their differentiation process, developing sieve tube members will also lose some of their cell contents to the translocation stream.…”