Activation of 80S Maize Ribosomes by Red Light Treatment of Dark-grown Seedlings

The in vitro protein synthetic activity of 80S ribosomes from leaves of dark-grown corn seedlings was enhanced (at low Mg²⁺ levels) by a 5-minute red light treatment applied 2 hours prior to tissue harvest. The effect was completely reversed by an immediate brief far red treatment, suggesting that ribosome activation is controlled by the phytochrome system. Experiments in which the interval between light treatment and tissue harvest was shortened indicate that the response was quite rapid. The initial increase in activity was detected within 30 minutes, followed by a rapid increase during the next 1.5 hours. No further increase occurred after 2 to 3 hours.