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Article summary:

1. Low temperatures have significant impacts on plant physiology and development, particularly in chloroplasts, which require resilience to cold temperatures for photoprotection, genome transcription, and other functions.

2. Chloroplast-encoded genes are transcribed by two RNA polymerases, including plastid-encoded plastid RNA polymerase (PEP) that requires a σ70-like sigma factor for promoter recognition and transcription initiation.

3. The sigma factor SIG5 plays a role in integrating low-temperature signals with circadian regulation of specific chloroplast transcripts, as well as responses to light conditions and various abiotic stresses.