A plant sustains pathogen-induced damage to one of its cell walls. A gene-for-gene response soon follows and the tissue surrounding the injury soon dies. Which signaling molecules facilitated this response?

Question

A.  Oligosaccharins
B.  Ethylene
C.  Gibberellins
D.  Auxins
E.  Abscisic acid

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
· What key words does the question contain and what do they mean?

Gather Content
· What do you already know about injury response in plants? How does it relate to the question?

Consider Possibilities
· What other information is related to the question? Which information is most useful?

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

A.  Oligosaccharins

Clarify Question
· What is the key concept addressed by the question?
        o The question is asking about the signaling molecules that initiate response to injury in plants.
· What type of thinking is required?
        o You are being asked to take what you already know and apply it to the response of a plant to tissue damage.
· What key words does the question contain and what do they mean?
        o Pathogen-induced, which means a disease-causing agent is responsible.
        o Gene-for-gene, which is a response that aids pathogen recognition.
        o Signaling molecules, which carry chemical message to tissues.

Gather Content
· What do you already know about injury response in plants? How does it relate to the question?
        o Oligosaccharins are found in cell walls.
        o The hypersensitive response is a gene-for-gene response that causes tissue death in the area surrounding the injury.
        o Tissue death inhibits the ability of the pathogen to spread.

Consider Possibilities
· What other information is related to the question? Which information is most useful?
        o Ethylene promotes fruit ripening and leaf, flower, and fruit abscission.
        o Gibberellin promotes stem elongation and production of enzymes in germinating seeds.
        o Auxin has many functions, but is not involved in the hypersensitive response.
        o Abscisic acid inhibits bud growth, plays a role in seed dormancy, inhibits other hormones, and controls stomatal closure.

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o The other chemicals mentioned do not play a direct role in signaling that results in a hypersensitive response.  When a cell wall is damaged by a pathogen, evidence suggests that oligosaccharins are released and a hypersensitive response occurs.

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
· Apply level:
        o This question asked you to assess the hypersensitive response in a plant.  Answering this question correctly depended on your ability to use the mechanics of this response in a new situation.  If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you remember that oligosaccharins are found in cell walls, and that they are released when the cell wall is damaged? Did you have trouble extending the presence of these molecules to determine the correct answer?