Comparison of UV and visible autofluorescence of wheat grain tissues in macroscopic images of cross-sections and particles

Many plant tissues can be observed thanks to the autofluorescence of their cell wall components. Multispectral autofluorescence imaging at the macroscopic scale is a rapid efficient way of observing samples with a large field of view (>1 cm2) and a nice resolution (<3 μm per pixel). The objective of this work was to evaluate autofluorescence multispectral imaging at the macroscopic scale to identify the tissular origin of particles through their autofluorescence profiles. The pericarp and aleurone layer of wheat grain were used to compare contrasted autofluorescence profiles measured in cross sections and particles. Air and water mounting media were tested. Principal component analysis and variance analysis showed that the autofluorescence properties were retained from cross sections to particles. The mounting media modified the autofluorescence profiles and water was found to be better to observe both particles and sections. These results show that multispectral autofluorescence imaging at the macroscopic scale can be used to identify the histological origin of particles.