Regulation of protochlorophyllide synthesis genes in darkness by class I TCP transcription factors TCP14 and TCP15 prevents photodamage after illumination in Arabidopsis.

Class I TCP transcription factors TCP14 and TCP15 repress protochlorophyllide synthesis genes in darkness, preventing photodamage during Arabidopsis de-etiolation.

• Why it matters: Controlling protochlorophyllide levels is crucial because excess accumulation can cause cellular damage upon light exposure, yet the regulatory mechanisms in darkness are not fully understood.
• What they did: The study used molecular and protein interaction analyses to show that TCP14 and TCP15 enhance PIF4 binding to target genes, modulating Pchlide synthesis, with their repressive role lost during illumination.
• The result: This regulation prevents photodamage in darkness by limiting chlorophyll precursor synthesis, and the TCPs switch to activating Pchlide genes under light, supporting proper chloroplast development.