Ethylene-dependent effects of fusaric acid on the photosynthetic activity of tomato plants

Fusaric acid (FA) is one of the potential toxins produced by pathogenic Fusarium species which exerts oxidative stress and cell death in plants. In this work, the effects of different concentrations of FA were investigated on the photosynthetic activity in leaves of wild type and Never ripe (Nr) tomato plants to reveal the potential role of ethylene under mycotoxin exposure. FA induced a significant ethylene emission from leaves in a concentration- and time-dependent manner. FA (1 mM) decreased the maximal and effective quantum yields of PSII and PSI in both tomato genotypes but photoprotective processes, such as the nonphotochemical quenching and the cyclic electron flow, were activated more effectively in Nr plants. However, the lipid peroxidation was higher in leaves of Nr. Our result confirmed that Nr plants were more sensitive to FA phytotoxicity suggesting the key role of ethylene in the activation of defense responses.