Cell wall mutations have been identified in six stages of primary wall biogenesis
A powerful new way to begin to probe function of individual polymers and even individual monosaccharide and polyphenol components is through identification and characterization of cell-wall mutants. Several categories of wall mutants have been identified, but the total collection is still quite small. At least six stages of biogenesis must be considered—substrate generation, synthases and glycosyl transferases, the secretory pathway, wall assembly, wall dynamics, and wall disassembly.

1. Pathways of substrate generation
  1.1 Nucleotide-sugar interconversion pathways
  1.2 C-1 kinases and sugar salvage pathways
  1.3 Pathways of phenylpropanoid biosynthesis


2. Polysaccharide synthases and glycosyl transferases
  2.1 Cellulose synthases
  2.2 Cellulose synthase-like Genes
  2.3 Glycosyl transferases
      2.3.1 GT family 8
      2.3.2 GT family 47
      2.3.3 GT family 37
      2.3.4 GT family 34
  2.4 Callose synthase genes
  

3. Secretion and targeting pathways
  3.1 Vesicle trafficking
  3.2 Cytoskeleton-associated proteins
  3.3 Plasma membrane fusion
  3.4 Endocytosis
  3.5 Cell-plate formation


4. Assembly, Architecture, and Growth
  4.1 Growth modifying proteins
      4.1.1 Expansins
      4.1.2 Yieldins
  4.2 Xyloglucan endotransglucosylase/hydrolases
  4.3 Hydrolases
      4.3.1 Exo-acting glycanases
          4.3.1.1 ß-Galactosidase family 35
      4.3.2 Endo-acting glycanases
          4.3.2.1 Glycoside hydrolase family 9 (Endo-1,4-beta-glucanase)
          4.3.2.2 Glycoside hydrolase family 17 (Glucan endo-1,3-beta-glucosidase)
      4.3.3 Polygalacturonases - PGases
  4.4 Lyases
      4.4.1 Pectate and pectin Lyases
      4.4.2 Rhamnogalacturonan I lyases
  4.5 Esterases
      4.5.1 Pectin methyl esterases
      4.5.2 Pectin acetylestereases
      4.5.3 Feruloyl esterases
  4.6 Structural proteins
      4.6.1 Hydroxyproline-rich glycoproteins (HRGPs)
      4.6.2 Proline-rich proteins (PRPs)
      4.6.3 Glycine-rich proteins (GRPs)
      4.6.4 Arabinogalactan-proteins (AGPs)


5. Differentiation and Secondary Wall Formation
  5.1 Lignan synthesis
  5.2 Lignin assembly and modification
      5.2.1 Laccases
      5.2.2 Peroxidases
      5.2.3 Germin-like proteins
  5.3 Cellulose and associated matrix polysaccharides


6. Signaling and Response Mechanisms
  6.1 Generation of signal molecules
  6.2 Reactive-oxygen species generation
  6.3 Receptor-like kinases and their ligands
  6.4 Glycosylphosphatidylinositol (GPI)-anchored proteins
      6.4.1 Phytocyanins
          6.4.1.1 Early nodulin like
          6.4.1.2 Uclacyanin-like       
          6.4.1.3 Stellacyanin-like
      6.4.2 Extensin-related
      6.4.3 Receptor-like
      6.4.4 HIPL
      6.4.5 Proteases
      6.4.6 LPTL
      6.4.7 GPDL
      6.4.8 COBRA family
      6.4.9 SKU5 family
      6.4.10 GPI-Anchored peptide (GAPEP) family
      6.4.11 Unknown GPI-anchored proteins


7. Unknowns

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