Effects of auxin analogues and heat stress on garden pea

The biochemical responses of high temperature (HT) stressed garden pea (Pisum sativum L.) pre-treated with the auxins 1-[2-chloroethoxycarbonyl-methyl]-4-naphthalenesulfonic acid calcium salt (TA-12) and 1-[2-dimethyla minoethoxicarbonylmethyl] naphthalene chlormethylate (TA-14) were studied. The HT stress caused an increase in lipid peroxidation in leaves indicating the occurrence of oxidative stress. The concentration of free proline and hydrogen peroxide (H2O2) decreased, while the total phenolics, free thiols and the activity of catalase (CAT), superoxide dismutase (SOD) and guaiacol peroxidase (POX) were increased in the high temperature stressed plants. The pre-treatment with auxins mitigated the oxidative stress provoked by HT treatment. The favourable effect of these auxin-like compounds was interpreted in relation to their ability to counteract the oxidative stress caused by high temperature in pea plants. The auxin analogues maintained the concentrations of non-enzymatic antioxidants and the activities of defence enzymes scavenging reactive oxygen species to equal or near to normal physiological level. Based on the obtained data, we suggest that exogenous application of TA-12 and TA-14 alleviates the harmful effect of high temperature in pea.