Abstract
An electron spin resonance (ESR) measurement technique using a spin probe has been developed for the observation of redox states within a plant under stress conditions. Spin probes are reduced in a leaf, and reoxidized through the oxidative transition of the leaf redox states. In this study, we investigated the stress response reactions of a spin probe on purpose to estimate the plant stress-response ability.
A carbamoyl-PROXYL used generally was introduced into a radish seedling and the ESR signal changes induced by light irradiation were monitored. The signal increments in an individual leaf depended on both the light intensities and the introduced carbamoyl-PROXYL amounts. A leaf of the previously photodamaged seedling exhibited significantly large increases of the ESR signals, which corresponded the loss of chlorophyll fluorescence quantum yield. These results indicate that the oxidative-stress adaptation of an individual leaf can be determined with the ESR technique.
