How would one track a mineral nutrient in a plant in order to prove that nutrient has been re mobilized?

Question

Before abscission - senescence of a plant structural components that contain mineral nutrients (E.g. Magnesium, Potassium...) are re-mobilized from the senescent tissue and used in other plant tissue for anabolic activities.

Could we design an experiment to prove this?

I was told that radioisotope method would work. We can detect the presence of the radioactive particle in one part at a time-point, but how would we know whether it is the very same particle that shows up elsewhere after abscission?

Answer 1

It is not possible to track individual molecules within a plant. However, one can track the level of radioactivity from place to place. So, in the case you are talking about, one would find that some level of radioactivity persisted for a time at one location, then it is observed to decline while it increases in another. There also might be a delectably increased level of radioactivity along the pathway between those two areas - regardless, one would logically connect decreased activity in one area with increased activity in another.

Answer 2

Magnesium isotopes would allow you to track the movement of magnesium.

Injection of the radioisotope 28Mg (half-life of 20.915 hours) into senescent cells may allow you to observe the direct effect of magnesium movement from senescent cells to other cells. If abscission were to occur, you could check abscised plant tissue. If you wanted to check if anabolism was also occurring, this may take more thought.

This is assuming senescents and abscission in the plant model takes under ~20 hours. Which I think is unlikely, however there are plenty of other 'mineral nutrient' and magnesium radioisotopes available.

Note
Radioactive isotopes have the ability to emit radiation allowing them to be imaged. This is great when they are inorganic molecules, because plant tissue is (mostly) organic. These variables allow imaging to be highly effective at particular emissions.

A similar approach was done here (Pay-wall(another here with-out paywall)). However these studies added another step 'fractionation'. This may be a helpful idea, fractionation is a separation process to measure the abundance of Magnesium (they refer to it as Magnesium Purification). This is another reason to use an isotope, instead of imaging it may be useful for purification.