Ethylene production and metabolism of 1-aminocyclopropane-1-carboxylic acid in a long-day plant,Chenopodium murale L., as influenced by photoperiodic flower induction

Chenopodium murale plants, induced to flower by 5 days of continuous light, produced 43% more ethylene than vegetative plants kept under short days (16 h darkness, 8 h light). The 1-aminocyclopropane-1-carboxylic acid (ACC)-induced ethylene production, using saturating ACC concentration (10 mol·m⁻³) was also 55% higher in induced plants. Their ACC and N-malonyl-ACC (MACC) levels were also higher, the former increasing by 56% in both shoots and roots, the latter by 288% and 108% in shoots and roots, respectively. Administration of labeled 2,3-¹⁴C]ACC produced a very similar relative content of ACC and MACC in both treatments. The only process influenced by flower induction was ACC conversion to ethylene. Induced plants converted 66% more ACC than the vegetative ones. The effects of photoperiod on ethylene formation and metabolism in a long-day plant (LDP)C. murale and a short-day plant (SDP)C. rubrum are compared. Ethylene formation seems to be under photoperiodic control in both species, but its role in flower induction remains obscure.