1. Plant cell walls (Ch. 15) 2. Dendrochronology.
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Transcript of 1. Plant cell walls (Ch. 15) 2. Dendrochronology.
1. Plant cell walls (Ch. 15)
2. Dendrochronology
Glucan chainsmay have 1000s to 10,000s of glucose residues
Some of the many compounds found in heartwood(of giant sequoia). Many are not cell wall compounds.
Lamlom & Savidge2006.
Cellulose microfibrils are synthesized at plasmamembraneby “particle rosettes” that includecellulose synthase.
Cell wall matrix polysaccharides synthesized in Golgi app and secreted to wall via membrane vesicle.
Matrix polysaccharidesHemicelluloses
xyloglucanglucuronoarabinoxylansglucomannans
Pectins are gel-formingpolysaccharide components of cell wall matrix
Secondary walls contain lignin that displaces water, binds cellulose, and prevents cell expansion.
Orientation of cellulose microfibrils determines direction of cell expansion.
Rate of cell expansion determined by cell wall extensibility and turgor pressure
Tree rings and dendrochronology
Diffuse porous Ring porous
Tree rings for reconstructing pastclimate
CO2 fertilizationinsect outbreaks
fire historyforest stand demography
Tree rings record insect outbreaks.Pandora moth on ponderosa pine.
Tree rings and forest demographics