Study on in situ analysis of cellulose, hemicelluloses and lignin distribution linked to tissue structure of crop stalk internodal transverse section based on FTIR microspectroscopic imaging

Crop stalks are an important source of lignocellulosic biomass, and have been broadly developed as one kind of renewable resources. Tissue compositional heterogeneity linked to crop stalks anatomy is attractive to plant researchers and researchers in the field of the biomass-refinery. This study is to develop a high-efficiency and rich-information characterization technique based on Fourier transform infrared (FTIR) microspectroscopic imaging for achieving an insight into the crop stalks, in which corn and cotton are taken for example, by creatively “seeing” crop stalks tissue structure in a chemical sense. Chemical images of cellulose, hemicelluloses and lignin that can be intuitively linked to tissue structure were produced based on FTIR microspectroscopic imaging with diagnostic spectral peaks. The principal components analysis was then applied to reveal the major spectral variances among different tissues. For cotton stalk transverse section, lignin is highly distributed in the xylem, while cellulose is uniformly distributed, and hemicellulose is highly distributed in the pith, in contrast to lignin. For corn stalk internodal transverse section, lignin is concentrated in the mechanical tissues, and again, cellulose is relatively uniformly distributed, while hemicellulose is concentrated in the parenchymal cells, in contrast to lignin. The results show that FTIR microspectroscopic imaging is an ideal technique for analyzing the chemical characterization linked to tissue structure in crop stalk transverse section.