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Bryant Adams – Wells College Alan Collmer – Cornell University

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102 diapositives · 1.4K Views · Jul 20, 2014

TM. Prototype 7/18/12 Revised 7/22/13. Bryant Adams – Wells College Alan Collmer – Cornell University Candace Collmer – Wells College and Cornell University Magdalen Lindeberg – Cornell University. Funding from:.

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Bryant Adams – Wells College Alan Collmer – Cornell University
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  1. TM Prototype 7/18/12 Revised 7/22/13 Bryant Adams – Wells College Alan Collmer – Cornell University Candace Collmer – Wells College and Cornell University Magdalen Lindeberg – Cornell University Funding from:

  2. As you know, microorganisms – microbes for short – can cause disease

  3. … for example, The Black Death – The Plague – began in Europe in the mid 1300s, killing ~25 million people …. ...then, as now, caused by infection with the bacterium called Yersinia pestis

  4. …but people also die from starvation due to plant disease – like the potato blight that caused the Irish Potato Famine, 1845-1852… …1 million died of starvation and a million more emigratedfrom Ireland

  5. … and the same pathogen that killed potatoes devastated tomatoes just recently in NY state. Late blight on tomato,2009

  6. But disease resulting from contact with microbes is the exception to the rule…

  7. But disease resulting from contact with microbes is the exception to the rule… Actually, hundreds to thousands of microbes come into contact with larger organisms that could become hosts to these potential microbial pathogens…..

  8. But disease resulting from contact with microbes is the exception to the rule… Actually, hundreds to thousands of microbes come into contact with larger organisms that could become hosts to these potential microbial pathogens….. …true for humans as well as plants…

  9. But disease resulting from contact with microbes is the exception to the rule… Actually, hundreds to thousands of microbes come into contact with larger organisms that could become hosts to these potential microbial pathogens….. …true for humans as well as plants… … yet only a tiny proportion of these microbes actually become pathogens on hosts – why?

  10. There’s an ongoing battle at the plant’s surface…

  11. There’s an ongoing battle at the plant’s surface… Pathogensaretrying to invade plants Plants are trying to detect these potential invaders and defendagainst them

  12. In the game VEGEVADERS,the battle is between: • the bacterial plant pathogenPseudomonas syringae (a relative of the animal pathogen that causes Plague and The Black Death) • and • a plant we rely on for food, like a tomato Bacteria on a leaf surface Disease symptoms on a plant leaf

  13. … and they fight it out through molecular interactions – how?

  14. Potential pathogens (bacteria here) have FEATURES = • specificmolecules that signal potential trouble if a plant recognizes them ...

  15. … for example, molecules found in the bacterial flagellum(for mobility).

  16. These can be recognized by PLANT Surface RECEPTORS via a specific “lock-and-key” match, which then initiates a response from the plant.

  17. Think of these potentially interacting pathogen and plant molecules using the following medieval castle metaphor:

  18. The Plant Cell = a Medieval Castle

  19. B A Plant Surface Receptors = specialized Lookouts on the castle’s wall, The Plant Cell = a Medieval Castle

  20. B A A Plant Surface Receptors = specialized Lookouts Specific Featureson a Bacterial Cell = different Flags on a potential Invader C D Plant Cell = a Medieval Castle B (= a single bacterium)

  21. … and Lookouts can only see matching Flags - Here, LookoutsA or B detect Features A or B B A A Plant Surface Receptors = specialized Lookouts Bacterial Features = different Flags C D Plant Cell = a Medieval Castle B (= a single bacterium)

  22. Then…. 1 1 B A 1) Detection by Lookouts A & B 3 (inside the plant cell) 2

  23. Then…. 1 1 B A 1) Detection by Lookouts A & B 3 → 2) a Signal sent inside the Castle (cell) (inside the plant cell) 2

  24. Then…. 1 1 B A 1) Detection by Lookouts A & B 3 3 → 2) a Signal sent inside the Castle (cell) (inside the plant cell) 2 → 3) a Defense Response = here, strengthening of the wall

  25. When PLANT Surface RECEPTORS detect Microbial FEATURES, a signal is sent to the inside of the plant cell … A A

  26. … which turns onMicrobe-Triggered Immunity (or MTI), which thickens the cell wall and stops the pathogen A A

  27. Microbe-Triggered Immunity(MTI) = the first, and most ancient, line of plant defense against pathogen attack A A

  28. Look at your VEGEVADERS play mat a single microbe E H F G H D A B C E H F G D A B C C1 C2 B2 a single plantcell B1 F2 D2 D1 E1 E2 F1 G1 G2 H1 H2 A1 A2 C1 C2 B2 B1 D2 E1 E2 G1 G2 H1 H2 A1 A2 F1 D1 F2

  29. Cards played in Row 1 = different Microbial Features of a single microbe E F G H 1 D A B C H E F G H 2 D A B C B1 C1 C2 B2 D2 F2 D1 E1 E2 F1 G1 G2 H1 H2 A1 A2 3 C1 C2 B1 B2 D1 D2 E1 E2 F1 F2 G1 G2 H1 H2 A1 A2 4

  30. Cards played in Row 1 = different Microbial Features of a single microbe E F G H 1 D A B C H Cards played in Row 2 = different Plant Surface Receptors in a single plant cell E F G H 2 D A B C B1 C1 C2 B2 D2 F2 D1 E1 E2 F1 G1 G2 H1 H2 A1 A2 3 C1 C2 B1 B2 D1 D2 E1 E2 F1 F2 G1 G2 H1 H2 A1 A2 4

  31. The Pathogen player plays Microbial Feature cards in Row 1, The Plant player plays Plant Receptor cards in Row 2, and Matching letters (like A with A) = detectionof a Microbial Featureby a Plant Receptor(and a resulting defense response). A 1 A 1 Microbial Feature 2 A 2Plant Surface Receptor A A1 A2 A1 A2

  32. In the game, 2 different pairsof matching Feature/Receptor cardsare required for the Plantto achieve MTI, and win. A 1 1 Microbial Feature A MTI 2 A 2Plant Surface Receptor A A1 A2 A1 A2

  33. On the mat, here is an example of two matches between Microbial FEATURE cards (or InvaderFlags in Row 1) and PLANT RECEPTOR cards (or Lookouts in Row 2), so that Plant achieves MTIand is winning…. so far…. F F B A D E H F G H D A B C E H F G D A D G B C C C1 C2 B2 B1 F2 D2 D1 E1 E2 F1 G1 G2 H1 H2 A1 A2 C1 C2 B2 B1 D2 E1 E2 G1 G2 H1 H2 A1 A2 F1 D1 F2

  34. In nature, Pathogens that were detected (via MTI) failed in their invasion attempt… So - you might wonder - why aren’t the plants alwayswinning??? A A

  35. Bacteria are not all identical. Each has small differences in its DNA, some of which enable an individual to invade and survive.

  36. How? What differences could help bacteria get around the plant’s Microbial Feature-Triggered Immunity (MTI)?

  37. One possibility – the recognized FEATURE might be lost ormutatedso it is no longer detected by the plant. Possible, but some features are really important for the bacteria’s survival and their loss would have serious consequences A

  38. Alternatively, surviving pathogens could have something new and different, like injected EFFECTOR PROTEINS that give them a selective advantage…

  39. Indeed, many pathogens that cause disease today inject EFFECTOR PROTEINS into the plant cell, where they shut downthe plant’s MTI...

  40. By analogy, the Invading bacterium injects daggered Invaders (Effectors) through the wall, inside the castle (cell)… B A A (Castle = a plant cell) C D B1 B ( = Bacterial Effectors) A1 C2 (a single bacterium)

  41. B A B1 (inside the plant cell) ... and Effectors are able to disable, or shut down, specific components of the MTI defense response: B1 shuts down B, A1 (or, alternatively, A2) shuts down A, etc. A1 C2

  42. On the VEGEVADERS play mat, the cards played in Row 3represent the differentMicrobial Effectors( = Invading Proteins ) A 1 A 1 Microbial Feature 2 A 2 Plant Surface Receptor A A1 A2 3 Microbial Effector 3 C1 C2 A1 A1 A2

  43. … and a played EFFECTORcardin Row 3 that matches the letter of a FEATURE-RECEPTOR pair in Rows 1 and 2 disables that pair. 1 F B A D E H F G H D A B C 2 C F F D G E H F G D A B C C1 C2 B2 B1 F2 D2 D1 E1 E2 F1 G1 G2 H1 H2 A1 A2 E2 D1 B1 H2 3 C1 C2 B2 B1 D2 E1 E2 G1 G2 H1 H2 A1 A2 F1 D1 F2 4

  44. … and a played EFFECTORcardin Row 3 that matches a FEATURE-RECEPTOR pair in Rows 1 and 2 disables that pair.Here, Effector D1 in Row 3 disables the D-D pair in Rows 1 and 2. 1 F B A D E H F G H D A B C 2 C F F D G E H F G D A B C C1 C2 B2 B1 F2 D2 D1 E1 E2 F1 G1 G2 H1 H2 A1 A2 E2 D1 B1 H2 3 C1 C2 B2 B1 D2 E1 E2 G1 G2 H1 H2 A1 A2 F1 D1 F2 4

  45. … and a played EFFECTORcardin Row 3 that matches a FEATURE-RECEPTOR pair in Rows 1 and 2 disables that pair.Here, Effector D1 in Row 3 disables the D-D pair in Rows 1 and 2. (Alternatively, EffectorD2could do the same job – only the letter needs to match.) 1 F B A D E H F G H D A B C 2 C F F D G E H F G D A B C C1 C2 B2 B1 F2 D2 D1 E1 E2 F1 G1 G2 H1 H2 A1 A2 E2 D2 B1 H2 3 C1 C2 B2 B1 D2 E1 E2 G1 G2 H1 H2 A1 A2 F1 D1 F2 4

  46. Note that now there is only one active FEATURE-RECEPTOR match, so at this point the Pathogen is winning (because the Plant does not have the 2 matches necessary for MTI ……) 1 F B A D E H F G H D A B C 2 C F F D G E H F G D A B C C1 C2 B2 B1 F2 D2 D1 E1 E2 F1 G1 G2 H1 H2 A1 A2 H2 E2 B1 D2 3 C1 C2 B2 B1 D2 E1 E2 G1 G2 H1 H2 A1 A2 F1 D1 F2 4

  47. Now, let’s lay down some cards and review: Pathogen player– Draw and lay down4 MicrobialFeature cards (light orange) in Row #1. (Discard and replace any duplicate card.)Plant player– Draw and lay down4 Plant Surface Receptorcards(light green) in Row #2. (Discard and replace any duplicate card.) 1 B G H D E H F G H D A B C E H F G A E F D 2 D A B C C1 C2 B2 B1 F2 D2 D1 E1 E2 F1 G1 G2 H1 H2 A1 A2 3 C1 C2 B2 B1 D2 E1 E2 G1 G2 H1 H2 A1 A2 F1 D1 F2 4

  48. First, on the mat below, are there 2 matches = Microbe-Triggered Immunity (MTI)? 1 B G H D E H F G H D A B C E H F G A E F D 2 D A B C C1 C2 B2 B1 F2 D2 D1 E1 E2 F1 G1 G2 H1 H2 A1 A2 3 C1 C2 B2 B1 D2 E1 E2 G1 G2 H1 H2 A1 A2 F1 D1 F2 4

  49. NO – only 1seen here, so noMicrobe-Triggered Immunity (MTI)? What about on your mat? (Tally results from around the class.) 1 B G H D E H F G H D A B C E H F G A E F D 2 D A B C C1 C2 B2 B1 F2 D2 D1 E1 E2 F1 G1 G2 H1 H2 A1 A2 3 C1 C2 B2 B1 D2 E1 E2 G1 G2 H1 H2 A1 A2 F1 D1 F2 4

  50. Pathogen player– now draw and lay down4 Effector cards (dark orange) in Row #3. Do you have on your mat an Effector in Row 3 that disables a Feature- Receptor match in Rows 1 and 2 (as seen below)? 1 1 G B H D E H F G H D A B C A F E D G 2 2 E H F G D A B C C1 C2 B2 B1 F2 D2 D1 E1 E2 F1 G1 G2 H1 H2 A1 A2 H1 F1 D1 B2 3 C1 C2 B2 B1 D2 E1 E2 G1 G2 H1 H2 A1 A2 F1 D1 F2 4 4