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Before abscission, senescence of a plant’s 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.

How could an experiment to demonstrate this?

I was told that a 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?

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  • $\begingroup$ You can't do it on a single-molecule level, but I'm in agreement with whoever told you to use radioisotopes. As to it being the same molecules, I would suspect that under most growing circumstances your plant isn't going to be exposed to neutron radiation or uptake radioisotopes from the environment to any significant degree., so the radioactive molecules would be the same ones you started with. $\endgroup$
    – Sol
    Aug 19, 2020 at 1:00
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    $\begingroup$ This looks like it was a homework question. Was it? $\endgroup$
    – David
    Sep 13, 2021 at 19:19

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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.

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    $\begingroup$ I suspect injection into already-senescent tissue is too late in the process to answer the OP's question. Perhaps a much earlier injection of a longer-lived isotope, then periodic testing over time to see if migration of the isotope occurs only/mostly with the onset of senescence. $\endgroup$
    – Armand
    Sep 15, 2021 at 0:54
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There are a variety of methods for visualizing elements in plants. Here is a review discussing various such methods.

  1. As suggested by other answers, radioisotopes are one such means (works in vivo?).
  2. One may also use X-ray spectroscopy: "With x-ray fluorescence-based approaches, elements are detected based upon their characteristic fluorescent x-rays. These fluorescent x-rays are generated by passing the specimen through a focused beam of high-energy x-rays (XFM), electrons (SEM- and TEM-EDS), or protons (PIXE)."
  3. Various electron microscopy methods, sometimes in combination with X-ray or radiography methods.
  4. Fluorescent tagging of elements with high-affinity fluorophores (works in vivo?).
  5. X-ray fluorescence microscopy (XFM).
  6. etc., go look at the paper.

Here is a helpful graphic summarizing strengths and weaknesses of various approaches:

comparison of different methods for visualizing elementary compositions in plants.

If you are interested in non-destructive sampling for tracking over time, there are several methods available from that list.

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