Effects of acetic acid treatment on growth and pigment contents in barley

Abstract

Acetic acid (AA) is an organic acid and has been widely used as food preservative and a dietary spice in vinegar form. In addition to its therapeutic uses in its vinegar form, AA attenuates inhibitory effects of stress in plants. However, in some plant species toxic effects of AA have been found. Therefore, in this study, 0, 2.5 and 5 mM concentrations of AA were applied to 2-day-old barley (Hordeum vulgare L. cv. Bornova-92) seedlings for 2 days in order to investigate the possible toxic effects of AA. After treatments, seedlings were grown in AA-free conditions for 2 days to recover. AA inhibited root and shoot growth; decreased water content, fresh weight, chlorophyll, pheophytin, and carotenoid contents. However, anthocyanin and flavonoid contents, as well as the levels of UV-absorbing compounds and UV-B marker increased in the leaves of AA-treated plants. AA increased hydrogen peroxide (H2O2) content in shoots and induced cell death in roots. Soluble carbohydrate content decreased in roots of AA-treated plants while insoluble carbohydrate content increased. Our results demonstrate that AA in young barley seedlings can exhibit its toxic effects through oxidative stress, which induced antioxidative response in the form of molecules with antioxidative activities. These effects persisted for 2 days after the removal of AA.