Isophorone‐induced light‐independent lipid peroxidation and loss of cell membrane integrity

Abstract

Isophorone (3,5,5‐trimethylcyclohex‐2‐en‐1‐one) is a plant‐derived volatile compound with strong phytotoxic activity. Here, we aimed to elucidate the mechanism of action of isophorone, and to this end, the effects of isophorone on shoot fresh weight, chlorophyll content, electrolyte leakage, and lipid peroxidation of Lactuca sativa L. and photosynthetic electron transport activity in chloroplast isolated from Spinacia oleracea L. were investigated. Isophorone induced light‐independent decreases in shoot fresh weight and light‐dependent chlorosis. In addition, increased electrolyte leakage and lipid peroxidation occurred under light conditions. However, the inhibitory activity on photosynthetic electron transport was unexpectedly low, and electrolyte leakage and lipid peroxidation were induced even under dark conditions. These results suggest that the inhibition of photosynthetic electron transport is not the main mechanism of action of isophorone and that the phytotoxic effects are mainly due to light‐independent oxidative damage and subsequent loss of cell membrane integrity.