Correct option is D
Detailed Explanation:
Statement A: In dark, high level of gibberellic acid (GA) helps DELLAs to directly bind to PIFs.
- This is incorrect. In the dark, DELLA proteins typically prevent the binding of PIFs to the promoters of genes by inhibiting their function. High levels of GA in the dark promote the degradation of DELLA proteins, which allows PIFs to bind and activate gene expression. So, DELLA proteins do not directly bind to PIFs in the dark but are instead stabilized by low GA levels.
Statement B: During light, the level of GA goes down and helps DELLA-PIF complex to bind to the promoters of the etiolation responsive genes.
- This is incorrect. In light, the levels of GA drop, leading to the degradation of DELLA proteins, which releases PIFs. These PIFs then bind to promoters of light-responsive genes, causing photomorphogenesis rather than continuing etiolation.
Statement C: Binding of DELLA proteins to PIFs prevents the transcription of PIF-induced genes, leading to photomorphogenesis.
- This is correct. In the dark, DELLA proteins bind to PIFs, preventing their interaction with DNA and the subsequent transcription of PIF-induced genes. This results in the inhibition of etiolation and activation of photomorphogenesis.
Statement D: Skotomorphogenesis is due to the degradation of DELLA proteins and binding of the PIFs to the etiolation responsive genes.
- This is correct. In the dark (skotomorphogenesis), the low levels of GA cause DELLA protein degradation, allowing PIFs to activate the transcription of etiolation-responsive genes that are involved in skotomorphogenesis, which is the process where plants elongate and grow without light.
