Improving cell walls

1
Improving cell walls
2
Should the hexose to pentose ratio of
hemicelluloses be modified?

• Would be of advantage, e.g. cellulose increase
• Major advantage for processing
• Change hemicellulose ratio decrease xylan at
  this stage difficult, but increase galactomannans
  possible -gt cell type specific promotors

3
Should the levels of noncyrstaline cellulose be
increased?

• increase in non-crystine should increase
  digestability
• Digestion in rumen it does not make a difference
  if crystaline or not
• G-layer -gt nearly pure cellulose -gt try to
  understand how this is made
• GPI-anchored protein KO lead to amorphous walls
  (sick plants)
• CesA protein mutation leads to a change
• Not a problem due to pretreatment

4
Can and should the levels or nature of lignin be
changed?

• Yes, see lecture John Ralph (insertion of ester
  zippers)
• Massive changes in composition possible -gt no
  detriment to plant growth
• Reduction not desirable due to energy recovery

5
What impact will be the biological consequences
of these changes?

• problematic

• Leave prim and sec. walls intact, but add
  additional polymers on top
• Wall prospecting -gt biology has been established

6
Can and should enhanced carbon flux into cell
walls be achieved?

• Oils, starch, fructans much better polymers
• Advantage deposition in apoplast fructans in
  vacuole

7
The optimal plant (utopia?)

• Huge oil content
• Large amounts of hexoses
• High yield/ acre
• Unzippable lignin
• Endogenous nitrogen fixation
• No water use
• No parasites/pathogens
• Provide number of ecoservices