Correct option is D
Ethylene: Ethylene is a plant hormone that works synergistically with JA to regulate defense responses against necrotrophic pathogens. In Arabidopsis, ethylene signaling, often through the transcription factor EIN3, enhances the expression of PDF1.2 in the presence of JA. Mutants defective in ethylene signaling, like ein2, fail to induce PDF1.2 even when JA is present, highlighting ethylene’s role. Applying exogenous ethylene or its precursors (like ACC, 1-aminocyclopropane-1-carboxylic acid) can upregulate PDF1.2, especially when JA signaling is also active. This makes ethylene another strong candidate for inducing PDF1.2.
The correct answer is (4) Ethylene.
Explanation:
The induction of defensin PDF1.2 in Arabidopsis is primarily regulated by ethylene signaling, especially in response to wounding. When plants are wounded or stressed, the production of ethylene is activated, which in turn induces the expression of defense-related genes, including PDF1.2. Ethylene plays a critical role in mediating the plant's defense responses to biotic and abiotic stresses. While wounding can trigger various signaling pathways, it is the ethylene pathway that directly leads to the induction of PDF1.2. This peptide is crucial for the plant's immune response, helping it resist infections and other threats.
Information Booster:
Ethylene is a key plant hormone involved in regulating stress responses to biotic and abiotic factors.
PDF1.2 is an antimicrobial defensin protein whose expression is induced by ethylene signaling following wounding or pathogen attack.
Ethylene works in conjunction with other signaling pathways, including jasmonic acid (JA), to activate defense responses, particularly in response to mechanical damage or herbivore attacks.
Defensin PDF1.2 plays a role in protecting the plant from pathogens by disrupting microbial cell walls and inhibiting pathogen growth.
The production of ethylene after wounding or pathogen attack helps in orchestrating a localized defense response by activating specific genes like PDF1.2.
Ethylene also interacts with other defense pathways, particularly those triggered by jasmonic acid (JA) and salicylic acid (SA), to fine-tune the plant's immune response.
Additional Information:
Option (1) Wounding activates various signaling pathways, including jasmonic acid (JA) and ethylene, but it is ethylene that directly leads to the induction of PDF1.2.
Option (2) Salicylic Acid (SA) is primarily involved in systemic acquired resistance (SAR) and is more associated with defense against biotrophic pathogens, rather than directly influencing the induction of PDF1.2.
Option (3) Dichloroisonicotinic acid (INA) is used in research to mimic the action of salicylic acid and activate SAR but does not directly induce PDF1.2 like ethylene does.
