Effects of Methyl jasmonate pretreatment on phenolic compounds and PAL activity in Lepidium sativum L. subjected to copper toxicity

Accumulation of phenolic compounds is considered as an important tool for environmental stress protection of plants. In this investigation, garden cress seedlings were in control conditions and were irrigated with Hoagland nutrient solution and were treated with methyl jasmonate (MeJ) at 0 (Control),5, 10 and 20 µM and different concentrations of copper 0 (Control), 50, 100 and 200 µM. Then shoot fresh weight, phenolic compounds content, anthocyanin content and PAL activity in response to treatments were measured. According to the results, shoot dry weight and PAL activity in treatment (5 μM) MeJ with (50 and 100 μM) copper, were significantly increased compared to control condition. Concentrations of MeJ (5 and 10μM) treated with 50 μM copper significantly increased the chlorophyll a, b, total chlorophyll and phenolic compound contents control conditions were compared. The results indicated that MeJ may act as a signaling molecule to enhance antioxidant pool and protected plants against injuries caused by Cu toxicity. Based on the results, determined that medium concentrations of MeJ (5 and 10 µM) had good effects on improvement of physiological effects in plants under cu toxicity.