FT-IR imaging and pyrolysis-molecular beam mass spectrometry: new tools to investigate wood tissues

Fourier transform infrared (FT-IR) microimaging spectroscopy and pyrolysis molecular beam mass spectrometry (py-MBMS) were used as rapid analysis tools to evaluate differences in the chemical composition of 1-year-old transgenic aspens. Multivariate analysis of the spectroscopic data sets was used to compare the cell wall composition of nontransformed control to transgenic aspen plants with GRP-iaaM gene and with GRP-iaaM/35S-ACCase gene. Principal component analysis (PCA) was applied to both the FT-IR and py-MBMS spectra, which revealed sample groupings due to differences in chemical composition. Evaluating the PCA loadings allows determination of the chemical features responsible for the groupings. The FT-IR microimaging data was also used to monitor changes in the chemical composition as a function of the distance from the pith to the bark using partial least squares (PLS) analysis. The analysis shows that the changes in the composition of the xylem that occur over one annual growth ring can be monitored with FT-IR microimaging.