Page 386 - Biosystems Engineering

Evaluation of Transgenic Wood for Pr oductivity & Quality 363

lignin content, syringyl-to-guaiacyl (S/G) ratio, cellulose, and xylose
content of transgenic aspen trees (Yamada et al. 2006). Pellets were
prepared from 75 mg of wood meal and directly scanned using trans-
mittance NIR spectroscopy. Very strong correlations were obtained
between the NIR data and conventional wet-chemistry results for the
lignin content, S/G ratio, cellulose, and xylose content. The results
indicate that transmittance NIR is a powerful tool for determining
and screening the chemical properties of transgenic trees.
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
composite of 1-year-old transgenic aspens (Labbé et al. 2005). In their
work, multivariate analysis of the spectroscopic data sets was used to
compare the cell wall composition of a nontransformed control to
transgenic aspen plants with the GRP-iaaM gene and with the GRP-
iaaM/35SACCase gene. Principal component analysis (PCA) was
applied to both the FT-IR and py-MBMS spectra, which revealed
sample groupings dues to differences in chemical composition. The
analysis showed that changes in the composition of the xylem that
occur over one annual growth ring can be monitored with FT-IR
microimaging. The py-MBMS provided detailed and specific infor-
mation on the chemical composition of the samples and is particu-
larly valuable for its ability to quickly, and unambiguously differenti-
ate syringyl and guaiacyl lignins and C6 and C5 sugars.

12.3.6 Impacts on Process and Utilization
Although much of the research on genetic modification was moti-
vated by a desire to improve wood for a more efficient and environ-
mentally friendly process, such as papermaking, very few transgenic
trees have yet been tested for understanding its impact on wood pro-
cess and utilization. Kraft pulping experiments on the wood of
2-year-old greenhouse-grown poplars resulted in a pulp with a lower
kappa number and an increase in brightness. This genetic improve-
ment may increase pulp throughput by 60 percent, concomitantly
with a decreased consumption of pulping chemicals (Huntley et al.
2003).
The fracturing properties of wood are important in relation to
wood processing including log sawing, thermomechanical pulping,
production of fiber or wood chips for use in wood composites, and
size reduction for bioenergy production. After comparing a control
radiate pine with genetically improved radiate (control pollinated
progeny from a single tree of the 850 family known as NZ850-55 or
clone 55), and New Zealand–grown spruce, Corson et al. (1989) found
that energy consumption for pulping to a specific freeness was sig-
nificantly lower in the genetically improved radiate pine when com-
pared to control-radiate pine.