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Pathogens Agrobacterium tumefaciens Agrobacterium rhizogenes Pseudomonas syringeae

Pathogens Agrobacterium tumefaciens Agrobacterium rhizogenes Pseudomonas syringeae Pseudomonas aeruginosa Viroids DNA viruses RNA viruses Fungi oomycetes nematodes Symbionts N-fixers Endomycorrhizae Ectomycorrhizae. Plant Growth Decide which way to divide & which way to elongate

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Pathogens Agrobacterium tumefaciens Agrobacterium rhizogenes Pseudomonas syringeae

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  1. Pathogens • Agrobacterium tumefaciens • Agrobacterium rhizogenes • Pseudomonas syringeae • Pseudomonas aeruginosa • Viroids • DNA viruses • RNA viruses • Fungi • oomycetes • nematodes • Symbionts • N-fixers • Endomycorrhizae • Ectomycorrhizae

  2. Plant Growth • Decide which way to divide & which way to elongate • Periclinal = perpendicular to surface: get longer • Anticlinal = parallel to surface: add more layers • Now must decide which way to elongate: which walls to stretch

  3. Plant Cell Walls and Growth Carbohydrate barrier surrounding cell • Protects & gives cell shape • 1˚ wall made first • mainly cellulose • Can stretch! • 2˚ wall made after growth stops • Lignins make it tough

  4. Plant Cell Walls and Growth • 1˚ wall made first • mainly cellulose • Can stretch! Control elongation by controlling orientation of cell wall fibers as wall is made • 1˚ walls = 25% cellulose, 25% hemicellulose, 35% pectin, 5% protein (but highly variable)

  5. Plant Cell Walls and Growth 1˚ walls = 25% cellulose, 25% hemicellulose, 35% pectin, 5% protein (but highly variable) Cellulose: ordered chains made of glucose linked b 1-4 • Cross-link with neighbors to form strong, stable fibers

  6. Plant Cell Walls and Growth Cellulose: ordered chains made of glucose linked b1-4 • Cross-link with neighbors to form strong, stable fibers • Made by enzyme embedded in the plasma membrane

  7. Plant Cell Walls and Growth Cellulose: ordered chains made of glucose linked b1-4 • Cross-link with neighbors to form strong, stable fibers • Made by enzyme embedded in the plasma membrane • Guided by cytoskeleton

  8. Plant Cell Walls and Growth Cellulose: ordered chains made of glucose linked b1-4 • Cross-link with neighbors to form strong, stable fibers • Made by enzyme embedded in the plasma membrane • Guided by cytoskeleton • Cells with poisoned µtubules are misshapen

  9. Plant Cell Walls and Growth Cellulose: ordered chains made of glucose linked b 1-4 • Cross-link with neighbors to form strong, stable fibers • Made by enzyme embedded in the plasma membrane • Guided by cytoskeleton • Cells with poisoned µtubules are misshapen • Other wall chemicals are made in Golgi & secreted

  10. Plant Cell Walls and Growth Cellulose: ordered chains made of glucose linked b 1-4 • Cross-link with neighbors to form strong, stable fibers • Made by enzyme embedded in the plasma membrane • Guided by cytoskeleton • Cells with poisoned µtubules are misshapen • Other wall chemicals are made in Golgi & secreted • Only cellulose pattern is tightly controlled

  11. Plant Cell Walls and Growth Cellulose pattern is tightly controlled • 6 CES enzymes form a “rosette”: each makes 6 chains -> 36/fiber

  12. Plant Cell Walls and Growth Cellulose pattern is tightly controlled • 6 CES enzymes form a “rosette”: each makes 6 chains -> 36/fiber • Rosettes are guided by microtubules

  13. Plant Cell Walls and Growth Cellulose pattern is tightly controlled • 6 CES enzymes form a “rosette”: each makes 6 chains • Rosettes are guided by microtubules • Deposition pattern determines direction of elongation

  14. Plant Cell Walls and Growth Cellulose pattern is tightly controlled • Deposition pattern determines direction of elongation • New fibers are perpendicular to growth direction, yet fibers form a mesh

  15. Plant Cell Walls and Growth New fibers are perpendicular to growth direction, yet fibers form a mesh Multinet hypothesis: fibers reorient as cell elongates Old fibers are anchored so gradually shift as cell grows

  16. Plant Cell Walls and Growth New fibers are perpendicular to growth direction, yet fibers form a mesh Multinet hypothesis: fibers reorient as cell elongates Old fibers are anchored so gradually shift as cell grows Result = mesh

  17. Plant Cell Walls and Growth 1˚ walls = 25% cellulose, 25% hemicellulose, 35% pectin, 5% protein (but highly variable) Hemicelluloses AKA cross-linking glycans: bind cellulose

  18. Plant Cell Walls and Growth Hemicelluloses AKA cross-linking glycans: bind cellulose Coat cellulose & bind neighbor

  19. Plant Cell Walls and Growth Hemicelluloses AKA cross-linking glycans Coat cellulose & bind neighbor Diverse group of glucans: also linked b 1-4, but may have other sugars and components attached to C6

  20. Hemicelluloses Diverse group of glucans: also linked b 1-4, but may have other sugars and components attached to C6 makes digestion more difficult

  21. Hemicelluloses Diverse group of glucans: also linked b 1-4, but may have other sugars and components attached to C6 makes digestion more difficult Assembled in Golgi

  22. Plant Cell Walls and Growth Hemicelluloses AKA cross-linking glycans A diverse group of glucans also linked b 1-4, but may have other sugars and components attached to C6 makes digestion more difficult Assembled in Golgi Secreted cf woven

  23. Plant Cell Walls and Growth 1˚ walls = 25% cellulose, 25% hemicellulose, 35% pectin, 5% protein (but highly variable) Pectins: fill space between cellulose-hemicellulose fibers

  24. Pectins Pectins: fill space between cellulose-hemicellulose fibers Form gel that determines cell wall porosity(& makes jam)

  25. Pectins Pectins: fill space between cellulose-hemicellulose fibers Form gel that determines cell wall porosity (& makes jam) Acidic, so also modulate pH & bind polars

  26. Pectins Pectins: fill space between cellulose-hemicellulose fibers Form gel that determines cell wall porosity (& makes jam) Acidic, so also modulate pH & bind polars Backbone is 1-4 linked galacturonic acid

  27. Pectins Backbone is 1-4 linked galacturonic acid Have complex sugar side-chains, vary by spp.

  28. Pectins Backbone is 1-4 linked galacturonic acid Have complex sugar side-chains, vary by spp.

  29. Plant Cell Walls and Growth Also 4 main multigenic families of structural proteins

  30. Plant Cell Walls and Growth Also 4 main multigenic families of structural proteins Amounts vary between cell types & conditions

  31. Plant Cell Walls and Growth Also 4 main multigenic families of structural proteins Amounts vary between cell types & conditions • HRGP: hydroxyproline-rich glycoproteins (eg extensin) • Proline changed to hydroxyproline in Golgi

  32. Plant Cell Wall Proteins • HRGP: hydroxyproline-rich glycoproteins (eg extensin) • Proline changed to hydroxyproline in Golgi • Highly glycosylated: helps bind CH2O

  33. Plant Cell Wall Proteins • HRGP: hydroxyproline-rich glycoproteins (eg extensin) • Proline changed to hydroxyproline in Golgi • Highly glycosylated: helps bind CH2O • Common in cambium, phloem

  34. Plant Cell Wall Proteins • HRGP: hydroxyproline-rich glycoproteins (eg extensin) • Proline changed to hydroxyproline in Golgi • Highly glycosylated: helps bind CH2O • Common in cambium, phloem • Help lock the wall after growth ceases

  35. Plant Cell Wall Proteins • HRGP: hydroxyproline-rich glycoproteins (eg extensin) • Proline changed to hydroxyproline in Golgi • Highly glycosylated: helps bind CH2O • Common in cambium, phloem • Help lock the wall after growth ceases • Induced by wounding 2. PRP: proline-rich proteins

  36. Plant Cell Wall Proteins • HRGP: hydroxyproline-rich glycoproteins (eg extensin) • PRP: proline-rich proteins • Low glycosylation = little interaction with CH2O

  37. Plant Cell Wall Proteins • HRGP: hydroxyproline-rich glycoproteins (eg extensin) • PRP: proline-rich proteins • Low glycosylation = little interaction with CH2O • Common in xylem, fibers, cortex

  38. Plant Cell Wall Proteins • HRGP: hydroxyproline-rich glycoproteins (eg extensin) • PRP: proline-rich proteins • Low glycosylation = little interaction with CH2O • Common in xylem, fibers, cortex • May help lock HRGPs together

  39. Plant Cell Wall Proteins • HRGP: hydroxyproline-rich glycoproteins (eg extensin) • PRP: proline-rich proteins • Low glycosylation = little interaction with CH2O • Common in xylem, fibers, cortex • May help lock HRGPs together • GRP: Glycine-rich proteins • No glycosylation = little interaction with CH2O

  40. Plant Cell Wall Proteins • HRGP: hydroxyproline-rich glycoproteins (eg extensin) • PRP: proline-rich proteins • Low glycosylation = little interaction with CH2O • Common in xylem, fibers, cortex • May help lock HRGPs together • GRP: Glycine-rich proteins • No glycosylation = little interaction with CH2O • Common in xylem

  41. Plant Cell Wall Proteins • HRGP: hydroxyproline-rich glycoproteins (eg extensin) • PRP: proline-rich proteins • Low glycosylation = little interaction with CH2O • Common in xylem, fibers, cortex • May help lock HRGPs together • GRP: Glycine-rich proteins • No glycosylation = little interaction with CH2O • Common in xylem • May help lock HRGPs & PRPs together

  42. Plant Cell Wall Proteins • HRGP: hydroxyproline-rich glycoproteins (eg extensin) • PRP: proline-rich proteins • 3. GRP: Glycine-rich proteins • No glycosylation = little interaction with CH2O • Common in xylem • May help lock HRGPs & PRPs together 4. Arabinogalactan proteins

  43. Plant Cell Wall Proteins • HRGP: hydroxyproline-rich glycoproteins (eg extensin) • PRP: proline-rich proteins • 3. GRP: Glycine-rich proteins • 4. Arabinogalactan proteins • Highly glycosylated: helps bind CH2O

  44. Plant Cell Wall Proteins • HRGP: hydroxyproline-rich glycoproteins (eg extensin) • PRP: proline-rich proteins • 3. GRP: Glycine-rich proteins • 4. Arabinogalactan proteins • Highly glycosylated: helps bind CH2O • Anchored to PM by GPI

  45. Plant Cell Wall Proteins • HRGP: hydroxyproline-rich glycoproteins (eg extensin) • PRP: proline-rich proteins • 3. GRP: Glycine-rich proteins • 4. Arabinogalactan proteins • Highly glycosylated: helps bind CH2O • Anchored to PM by GPI • Help cell adhesion and cell signaling

  46. Plant Cell Wall Proteins • HRGP: hydroxyproline-rich glycoproteins (eg extensin) • PRP: proline-rich proteins • 3. GRP: Glycine-rich proteins • 4. Arabinogalactan proteins • Highly glycosylated: helps bind CH2O • Anchored to PM by GPI • Help cell adhesion and cell signaling 5. Also many enzymes involved in cell wall synthesis and loosening

  47. Plant Cell Walls and Growth Also many enzymes involved in cell wall synthesis and loosening As growth stops, start making lignins & linking HGRP

  48. Plant Cell Walls and Growth As growth stops, start depositing lignins & linking HGRP Lignins = polyphenolic macromolecules: 2nd most abundant on earth (after cellulose)

  49. Plant Cell Walls and Growth Lignins = polyphenolic macromolecules: 2nd most abundant on earth (after cellulose) Bond hemicellulose: solidify & protect cell wall (nature’s cement): very difficult to digest

  50. Plant Cell Walls and Growth Lignins = polyphenolic macromolecules: 2nd most abundant on earth (after cellulose) Bond hemicellulose: solidify & protect cell wall (nature’s cement): very difficult to digest Monomers are made in cytoplasm & secreted

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