Gas exchange in dry seeds: circadian rhythmicity in the absence of DNA replication, transcription, and translation.

A 24-hour rhythm of gas exchange has been detected in dry onion seeds. The rhythm persists in constant conditions, and its period appears to be independent of temperature. Since DNA replication, transcription, and perhaps translation do not occur in this quiescent state, it is concluded that the basic oscillation that defines circadian rhythmicity does not derive directly from these processes.