Changes in cell wall composition and esterification
patterns in response to drought stress
In order to investigate the potential source(s) of MeOH and AA emissions
from poplar leaves and evaluate potential impacts of drought stress on
the cell wall polysaccharide composition, leaf bulk monosaccharide
composition was determined from AIR samples. Consistent with the
expected high pectin content of rapidly expanding leaf primary cell
walls, monosaccharide content of AIR from control poplar leaves was
dominated by galacturonic acid (GalA, Figure 10a ). While the
monosaccharide content, and by extension polysaccharide content of the
cell walls remained largely unchanged during drought, we observed an
increase in O -acetyl ester content during drought (Figure
10b ). AIR from control leaves released an average of 0.69 µg
g-1 of free acetate following saponification which
increased by 10% to 0.76 µg g-1 of free acetate
g-1 from drought stressed leaves. Leaf AIRO -acetyl ester content increased throughout the drought, reaching
a maximum after 7 days (Figure 10b ). After 7 days, the leaves
were fully desiccated, and subsequently detached from the tree.