Correct option is B
Explanation-
A. PIFs promote skotomorphogenesis by serving as transcriptional activators of dark-induced genes. - CORRECT
PIFs (Phytochrome Interacting Factors) are basic helix-loop-helix (bHLH) transcription factors. They are active in darkness and promote skotomorphogenesis (etiolated growth). In the dark, PIFs activate genes that repress photomorphogenesis and promote stem elongation.
B. PIFs on interaction with Pr get phosphorylated, followed by degradation via the proteasome complex. - INCORRECT
PIFs interact with the active form of phytochrome (Pfr), not Pr. Upon interaction with Pfr in light, PIFs are phosphorylated and targeted for degradation via the 26S proteasome. This degradation relieves repression of photomorphogenic genes.
C. The degradation of PIFs takes place in the presence of light. - CORRECT
Light converts phytochrome to its active Pfr form, which interacts with PIFs, leading to their phosphorylation and degradation. This is a key mechanism by which light promotes photomorphogenesis.
D. PIF-induced genes are not expressed in light. - CORRECT
In light, PIFs are degraded, so the genes they normally activate in darkness are not expressed. Thus, photomorphogenesis genes are turned on, and skotomorphogenesis genes are suppressed.
Correct Answer:
Option b : A, C and D only
