Electron Spin Resonance of 2,2,6,6-Tetramethylpiperidine-1-Oxyl (TEMPO)-labeled Plant Leaves

Abstract
Temperature dependence for partitioning of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) between aqueous and lipid components of whole leaf tissue was measured. TEMPO is an electron spin resonance nitroxide label that was used in model systems to detect membrane phase separations. Measurements were made on chilling-sensitive tomato [Lycopersicon esculentum cv. Super Sioux] leaves, frost-sensitive potato [Solanum tuberosum cv. Russet Burbank] leaves, and frost-hardy and supercooled wheat [Triticum aestivum cv. Cheyenne] leaves. The results suggest a membrane phase separation at 11.degree. C in tomato, 3.degree. C in potato and -11.degree. C in wheat.