- Jasmonate is known to inhibit root growth while auxin facilitates root growth. Upon infection with pathogenic bacteria that produce coronatine, we may expect the following in plants:
A. Upregulation of COI-1 gene and inhibition of root growth.
B. Upregulation of AuxI-1 gene and inhibition of root growth
C. Inhibition of Auxl-1 gene and promotion of root growth.
D. Inhibition of COI-1 gene and promotion of root growth.
Which one of the following is correct?
(1) A, B and C (2) Only A
(3) Only B (4) Only CCorrect answer: (2) Only A
Explanation:
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Jasmonate signaling, mediated by the COI1 receptor, is known to inhibit root growth as a defense strategy against stress or pathogen attack.
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Coronatine is a mimic of jasmonic acid produced by some pathogenic bacteria, activating jasmonate signaling pathways causing similar effects as JA hormone, including upregulation of COI1 gene function and root growth inhibition.
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Auxin signaling, via genes like Aux1-1, generally promotes root growth, but coronatine and JA signaling do not upregulate auxin inhibitors or genes that suppress root growth.
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Therefore, options B, C, and D involving changes in Aux1-1 expression or COI1 inhibition are incorrect.
Option-wise:
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(1) A, B and C — B and C false.
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(2) Only A — correct.
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(3) Only B — false.
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(4) Only C — false.
Coronatine from pathogenic bacteria activates jasmonate signaling by upregulating COI1, leading to inhibition of root growth in plants, a response that contrasts with auxin-driven root promotion, illustrating complex hormone interactions during pathogen attack.
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