Infrared microspectroscopic imaging of plant tissues: spectral visualization of Triticum aestivum kernel and Arabidopsis leaf microstructure

Frederick J Warren, Benjamin B Perston, Silvia P Galindez-Najera, Cathrina H Edwards, Prudence O Powell, Giusy Mandalari, Grant M Campbell, Peter J Butterworth, Peter R Ellis

Infrared microspectroscopy is a tool with potential for studies of the microstructure, chemical composition and functionality of plants at a sub-cellular level. Here we present the use of high resolution bench-top based infrared microspectroscopy to investigate the microstructure of wheat kernels and Arabidopsis leaves. Images of isolated wheat kernel tissues and whole wheat kernels following hydrothermal processing and simulated gastric and duodenal digestion were generated, as well as of Arabidopsis leaves at different points during a diurnal cycle. Individual cells and cell walls were resolved, and large structures within cells such as starch granules and protein bodies were clearly identified. Contrast was provided by converting the hyperspectral image cubes into false-colour images using either principal component analysis (PCA) overlays, or by correlation analysis. The unsupervised PCA approach provided a clear view of the sample microstructure, while the correlation analysis was used to confirm the identity of different anatomical structures using the spectra from isolated components. It was then demonstrated that gelatinised and native starch within cells could be distinguished, and the loss of starch during wheat digestion could be observed, as well as accumulation of starch during a diurnal period in leaves. This article is protected by copyright. All rights reserved.