Multispectral phloem-mobile probes: Properties and applications

Michael Knoblauch, Marc Vendrell, Erica De Leau, Andrea Paterlini, Kirsten Knox, Tim Ross-Elliot, Anke Reinders, Stephen A. Brockman, John Ward, Karl Oparka

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


Using Arabidopsis (Arabidopsis thaliana) seedlings, we identified a range of small fluorescent probes that entered the translocation stream and were unloaded at the root tip. These probes had absorbance/emission maxima ranging from 367/454 to 546/576 nm and represent a versatile toolbox for studying phloem transport. Of the probes that we tested, naturally occurring fluorescent coumarin glucosides (esculin and fraxin) were phloem loaded and transported in oocytes by the sucrose transporter, AtSUC2. Arabidopsis plants in which AtSUC2 was replaced with barley (Hordeum vulgare) sucrose transporter (HvSUT1), which does not transport esculin in oocytes, failed to load esculin into the phloem. In wild-type plants, the fluorescence of esculin decayed to background levels about 2 h after phloem unloading, making it a suitable tracer for pulse-labeling studies of phloem transport. We identified additional probes, such as carboxytetraethylrhodamine, a red fluorescent probe that, unlike esculin, was stable for several hours after phloem unloading and could be used to study phloem transport in Arabidopsis lines expressing green fluorescent protein.

Original languageEnglish (US)
Pages (from-to)1211-1220
Number of pages10
JournalPlant physiology
Issue number4
StatePublished - Apr 1 2015

Bibliographical note

Publisher Copyright:
© 2014 American Society of Plant Biologists. All rights reserved.


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