The phytohormones ethylene (ET), methyl jasmonate (MeJA) and salicylic acid (SA) play important roles in plant defense. The following statements were made regarding induction of defensin PDF1.2 and pathogenesis-related protein PR1:

A. ET/MeJA activates PDF1.2
B. ET/MeJA activates PR-1
C. SA activates PDF1.2
D. SA activates PR-1

Which one of the following options represents the combination of correct statements?

Correct option is B

Explanation-

​Plants use different signaling pathways to activate defense genes in response to various stresses. Among them, ethylene (ET) and methyl jasmonate (MeJA) work together in one pathway, while salicylic acid (SA) functions in a separate pathway.

Defense-related marker genes:
             PDF1.2 (Plant Defensin 1.2):  It is a marker for the ET/MeJA-dependent pathway. It is activated by ET/MeJA. It is typically associated with defense against necrotrophic pathogens and insects.
             PR-1 (Pathogenesis-Related Protein 1): It is a marker for the SA-dependent pathway. It is activated by salicylic acid (SA). It is typically associated with defense against biotrophic pathogens.

Statements:
A. ET/MeJA activates PDF1.2 → Correct
B. ET/MeJA activates PR-1 →  Incorrect (PR-1 is activated by SA, not ET/MeJA)
C. SA activates PDF1.2 →  Incorrect (PDF1.2 is activated by ET/MeJA, not SA)
D. SA activates PR-1 →Correct

Therefore, correct combination: A and D (Option b )