Tracking stable isotope enrichment in tree seedlings with solid-state NMR spectroscopy

Area of Science:

• Plant Physiology
• Biogeochemistry
• Analytical Chemistry

Background:

• Isotope enrichment in plant tissues is crucial for tracing elemental fluxes.
• Understanding molecular isotope allocation is vital for accurate tracer data interpretation.
• Current methods often overlook the detailed molecular distribution of isotopes.

Purpose of the Study:

• To develop a rapid, non-destructive method for quantifying molecular isotope allocation.
• To track the temporal fate of carbon-13 and nitrogen-15 in boreal tree seedlings.
• To investigate isotope distribution differences between plant tissues and molecules.

Main Methods:

• Utilized solid-state carbon-13 and nitrogen-15 nuclear magnetic resonance spectroscopy.
• Applied pulses of carbon-13 dioxide gas and potassium nitrogen-15 nitrate solution.
• Monitored isotope allocation in boreal tree seedling roots and leaves over time.

Main Results:

• Observed preferential carbon-13 enrichment in leaf carbohydrates, followed by redistribution to complex compounds within seven days.
• Found uniform carbon-13 allocation across molecules in roots.
• Detected initial nitrogen-15 enrichment in amine molecules within two hours in roots.

Conclusions:

• Solid-state NMR provides a powerful tool for detailed molecular isotope analysis in plants.
• Isotope allocation varies significantly among plant tissues and molecular types.
• This method enhances the precision of ecological tracer studies.