No abstract

Methyl jasmonate (MJ) is an important plant growth regulator that plays a key role in tolerance to biotic and abiotic stresses. In this research, the effects of exogenous MJ on cold tolerance, photosynthesis, activity and gene expression of antioxidant enzymes, proline accumulation, and expression of cold-regulated (COR) genes in wheat seedlings under low temperature (4 °C) were investigated. Exogenous MJ treatment (1 µM) promoted wheat cold tolerance before and during cold exposure. Low temperature significantly decreased photosynthetic parameters, whereas MJ application led to their partial recovery under cold exposure. Hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels increased in response to low temperature, and this was counteracted by MJ application. Exogenous MJ significantly enhanced the activities of antioxidant enzymes and upregulated the expression of MnSOD and CAT during cold exposure. MJ application also led to enhanced proline content before 4 °C exposure, whereas the P5CS gene expression was upregulated by MJ’s presence at both normal (22 °C) and low (4 °C) temperatures. It was also shown that MJ tended to upregulate the expression of the COR genes WCS19 and WCS120 genes. We conclude that exogenous MJ can alleviate the negative effect of cold stress thus increasing wheat cold tolerance.

No abstract

The cadmium effect (100 μM) on the barley (Hordeum vulgare L.) growth, the content of HvCu/ZnSOD, HvCAT2 and HvPRX07 transcripts and the antioxidant enzymes activity (SOD, CAT and PRX) in roots and leaves of seedlings under optimal (22 °C) and low (4 °C) temperatures were studied. Exposure to cadmium at 22 °C did not inhibit the plants' growth. In this case, the rate of the oxidative processes in the cells remained at the control level. This was achieved by a corresponding increase of the gene transcripts and the antioxidant enzymes activity in roots and leaves. In contrast, exposure to cadmium at 4 °C inhibited the seedlings' growth despite of the lower metal content in the plants. Moreover the rate of lipid peroxidation in the roots and leaves increased significantly. It is assumed that this effect was connected with the accumulation of excess amounts of hydrogen peroxide due to a misbalance between its generation and neutralization. This assumption is confirmed by the obtained data, according to which the level of HvCu/ZnSOD expression and the total activity of SOD increased significantly under exposure to cadmium at 4 °C, although HvCAT2 and HvPRX07 transcripts and CAT and PXR activity did not rise.