MS Imaging of Natural Toxin Colchicine in Autumn Crocus Bulb Using iMScope QT

Significance of the Topic

The precise localization of plant toxins is critical for understanding their biosynthesis, evaluating food safety risks and guiding breeding or mitigation strategies. Colchicine and demecolcine in the autumn crocus bulb pose a high fatality risk upon accidental ingestion, making visualization of their spatial distribution by mass spectrometry imaging a valuable tool for toxicology and plant science.

Aims and Study Overview

This application note demonstrates the use of a high-speed imaging mass microscope for mapping colchicine and demecolcine in cross sections of autumn crocus bulb. The goal is to reveal regional accumulation patterns of these toxins and to highlight the capabilities of rapid, high-resolution MS imaging for toxic compound analysis in plant tissues.

Methodology and Instrumentation

Sample Preparation:

• Autumn crocus bulbs halved longitudinally, fresh-frozen and cryosectioned at 30 µm thickness onto ITO-coated slides.

Matrix Application:

• CHCA matrix deposited uniformly at 0.7 µm thickness using the automated iMLayer™ system.

MS Imaging:

• Instrument: iMScope™ QT imaging mass microscope.
• Spatial resolution: 25 µm for full-section scans; 10 µm for detailed area scans.
• Acquisition speed: 20 kHz laser repetition rate, 50 shots per pixel.
• Mass range: m/z 370–405 in positive polarity.

Main Results and Discussion

Full-section imaging (25 µm pitch) generated ~378,600 pixels in under 4 hours. Colchicine localized predominantly at the peripheral scale tissue, whereas demecolcine exhibited a uniform distribution across the bulb. Higher-resolution imaging (10 µm pitch) confirmed these trends within the 10× optical field, demonstrating reproducibility at multiple spatial scales.

Benefits and Practical Applications

MS imaging with the high-throughput iMScope QT enables:

• Rapid mapping of toxic compounds in large plant samples.
• Flexible spatial resolution to balance speed and detail.
• Overlay of optical and mass images for precise anatomical correlation.

These capabilities support food safety research, plant metabolomics and toxin localization studies.

Future Trends and Application Opportunities

Advancements may include multimodal imaging combining MS with fluorescence or Raman microscopy, higher spatial resolution below 5 µm and automated data analysis pipelines. Such developments will enhance our understanding of toxin biosynthesis, support precision breeding and accelerate toxicology screening in other plant species.

Conclusion

The iMScope QT, combined with automated matrix deposition, provides a fast, reproducible platform for high-resolution MS imaging of plant toxins. Visualization of colchicine and demecolcine distributions in autumn crocus bulbs reveals distinct accumulation patterns, demonstrating the technique’s value in food safety and plant science.

Reference

Kaoru Nakagawa and Tetsuo Iida. MS Imaging of Natural Toxin Colchicine in Autumn Crocus Bulb Using iMScope QT. Shimadzu Application News, First Edition: Sep. 2024.