SPATIAL-DISTRIBUTION OF PHENOLIC MATERIALS IN DURUM-WHEAT GRAIN AS PROBED BY CONFOCAL FLUORESCENCE SPECTRAL IMAGING

Microspectrofluorometry has been employed to study the spatial distrib ution of phenolic material in cereal grain. Transverse sections of the grain were used for the spectral characterisation of different molecu lar species present in Triticum durum grains. Auto-fluorescence emissi on spectra were recorded on micro regions of each section. The analysi s of the whole set of spectra permitted the characterisation of three principal spectral features; indicators of phenolics in specific regio ns of wheat sections. The comparison with model reference spectra show ed that spectral components could be attributed to ferulic and p-couma ric acids. Using these spectral components, spectral fluorescence imag ing was performed allowing the relative fluorescence intensity of each phenolic feature to be mapped. Images generated were used for the gen eration of the 3D organisation of auto-fluorescent phenolic materials within the grain. This new and rapid method was further used for the s pectral characterisation of the various aleurone cell walls with high sensitivity. Analysis of the data showed that outer and inner aleurone cell walls exhibited similar fluorescence profiles but with significa ntly different intensities. (C) 1998 Academic Press.