Non-Autocatalytic Build-Up of Ribulose 1,5-bisphosphate during the Initial Phase of Photosynthetic Induction in Maize Leaves

A possible mechanism for the previous finding of a transientpeak of ribulose 1,5-bisphosphate (RuBP) in maize leaves duringinduction of photosynthesis [Usuda (1985) Plant Physiol. 78:859] was assessed. The transient peak in RuBP level during photosyntheticinduction was eliminated when a solution of NaHCO₃ was vacuum-infiltratedthrough vascular tissues. These results indicate that a limitedsupply of CO₂ to RuBP carboxylase is responsible for the transientpeak of RuBP. The possibility of a non-autocatalytic build-upof RuBP during the initial phase of induction is discussed. (Received January 13, 1986; Accepted March 14, 1986)