- Which one of the following is the correct function of JAZ (JASMONATE ZIM- DOMAIN) protein family, a key regulator of Jasmonic Acid (JA) signalling response?
(1) Binds to MYC2 and represses the JA dependent genes.
(2) Binds to MYC2 and transcribes JA dependent genes.
(3) Acts as receptor of JA signal.
(4) Involved in directly inducing JA dependent genes.JAZ (Jasmonate ZIM-domain) proteins are plant-specific transcriptional repressors that play a central role as negative regulators in the jasmonic acid (JA) signaling pathway. They function by binding to transcription factors such as MYC2 and repressing the expression of JA-dependent genes. In the absence of bioactive jasmonate, JAZ proteins inhibit these transcription factors, preventing the activation of JA-responsive genes. Upon jasmonate signaling, JAZ proteins are targeted for degradation via the SCF^COI1^ ubiquitin ligase complex, releasing MYC2 and other transcription factors to activate gene expression.
Explanation of options:
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(1) Correct. JAZ proteins bind to MYC2 and repress JA-dependent gene expression.
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(2) Incorrect. JAZ proteins do not transcribe genes; they repress transcription by binding to transcription factors.
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(3) Incorrect. JAZ proteins are not JA receptors; the JA receptor is the SCF^COI1^ complex.
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(4) Incorrect. JAZ proteins repress rather than directly induce JA-dependent genes.
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JAZ proteins are key repressors in jasmonic acid signaling, binding to MYC2 transcription factors and inhibiting JA-responsive gene expression; jasmonate perception triggers JAZ degradation releasing MYC2 to activate defense and developmental genes.
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