Labeling Maize (Zea mays L.) Leaves with

Area of Science:

• Plant physiology
• Biochemistry
• Agricultural science

Background:

• Nitrogen is essential for plant and animal life, primarily as proteins and amino acids.
• Atmospheric nitrogen is abundant but not directly usable by most organisms.
• Plants convert soil nitrate and ammonium into amino acids and proteins, forming a crucial part of the food chain.

Purpose of the Study:

• To describe a protocol for tracing the metabolic pathways of nitrogen (N) uptake and assimilation in plants.
• To quantify 15N enrichment in amino acids and proteins derived from labeled nitrate and ammonium.
• To enable the study of genetic modifications' effects on nitrogen and carbon metabolism.

Main Methods:

• Utilizing 15N-labeled nitrate and ammonium to trace nitrogen assimilation in plants.
• Employing gas chromatography followed by mass spectrometry (GC/MS) for detection and quantification.
• Extracting, purifying, and separating amino acids from maize leaves for analysis.

Main Results:

• A detailed protocol for quantifying 15N enrichment in maize leaf amino acids is presented.
• The method allows for the relative calculation of 15N enrichment in individual amino acids.
• Differences in amino acid accumulation dynamics can be identified.

Conclusions:

• The described protocol facilitates the study of nitrogen assimilation pathways in plants.
• This method is valuable for investigating the impact of genetic changes on plant metabolism.
• It provides insights into primary nitrogen and carbon metabolism in plants.