Measuring Phloem Transport Velocity on a Tissue Level Using a Phloem-Mobile Dye
Here we describe an in vivo dye-tracking method for measuring phloem transport velocity in seedlings, leaves and petioles and potentially other translucent plant tissues. The method requires measurement of the fluorescent signal of a phloem-mobile fluorescent dye using sensitive photo-sensors placed external to the plant. Following dye application, velocity is determined using laser fluorescence bleaching and measuring the time it takes for the bleach front to reach a light sensor. This method can be used to measure phloem transport velocity on intact plants with minimal disturbance and has a potential to be used under a variety of growth conditions and in the field. Because there are large differences among species in their anatomy, this method should be optimized to individual plants and tissue types.
Key wordsTransport velocity Carboxyfluorescein diacetate Fluorescence Phloem-mobile dyes Fluorescence bleaching FRAP Carbon allocation
This work was partially supported by the National Science Foundation Integrative Organismal Systems 1656318 (JAS).
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