Photorespiratory Oxygen Uptake in Isolated Bundle Sheath Strands of C4 Plants

Abstract

Bundle sheath strands were extracted from maize cv. DeKalb XL66, Panicum miliaceum and Chloris gayana, and O2 uptake and evolution were measured using isotopic mass spectrometry. All spp. showed some CO2 suppressible and apparently photorespiratory O2 uptake. The suppression by CO2 implied that RuBP carboxylase was involved. O2 uptake in C4 leaves might be due to bundle sheath reactions similarly to those in C3 leaves under high CO2 concn. The C4 bundle sheath showed a considerable capacity for photorespiration.