Abstract：Ochratoxin A (OTA) is one of the most toxic mycotoxins to both animals and plants. Ethylene (ETH), as a gaseous plant hormone, contributes greatly to a wide range of cellular and developmental processes, and it responses to abiotic and biotic stress. However, the role of ETH in OTA toxicity to Arabidopsis thaliana is not uncovered. In this study, ETH and the ethylene biosynthetic precursor 1-aminocyclopropane-1-carboxylic acid (ACC) content of A. thaliana leaves exposed to OTA were measured by high performance liquid chromatography. The results showed that OTA treatment increased ETH and ACC content in A.thaliana leaves. Quantitative Real-time PCR was performed to determine the relative expression level of ACC synthase gene 6 (ACS6) which is an important gene in ETH synthesis, and ACS6 expression was induced by OTA and the effect was related to the treatment time of OTA. When exogenous ACC with OTA was added to A.thaliana leaves, aggravated lesions, promoted relative leakage rate and increased reactive oxygen species content were observed, showing that ACC could intensify the damage of OTA to leaves. What was in contrast with the results above was that in the presence of the ethylene receptor antagonist Ag+ by addition of AgNO3, the toxicity of OTA to A.thaliana leaves was lessened. The research indicated the involvement of ETH in phytotoxicity of OTA as a possible negatively regulator. This study preliminary reveals the role and partly mechanism of ETH in phytotoxicity of OTA to A.thaliana, and can provide foundation for further research on the mechanism of phytotoxicity of OTA.
