Nondestructive real-time monitoring of the redox status in a potted plant by using a surface-coil-type ESR resonator

To perform nondestructive real-time monitoring of the redox state in plants against environmental stress, a 700-MHz surface-coil-type ESR resonator wa s employed and temporal changes in ESR signals of an exogenous nitroxide ra dical in the leaves of a potted tobacco plant were observed after chilling. ESR signals of the nitroxide radical were barely observed at room temperat ure, indicating that the nitroxide radical was reduced to the hydroxylamine by reductants in the leaves. Chilling significantly increased die signal-t o-noise ratios (S/Ns) of the nitroxide radical in the leaves. Because hydro xylamines are oxidized to nitroxide radicals by oxidants, it is thought tha t the ESR S/Ns can be used as an index for oxidation in leaves.