Effect of Seed Treatment with Salicylic Acid on the Carbonic Anhydrase Activity, Photosynthesis Rate, Stomatal Conductance, and Pigments Content in Wheat Leaves at Zinc Excess.

The effect of seed treatment with salicylic acid (SA) on the carbonic anhydrase (CA) activity, photosynthesis rate, stomatal conductance, and pigment content in wheat leaves was studied at an optimal zinc content (2 µM) and zinc excess (1500 µM). It was shown for the first time that the CA activity and stomatal conductance increased upon seed treatment with SA at the optimal zinc content as compared with untreated plants, while the photosynthesis rate was not affected. When zinc was in excess in the root zone, seed treatment with SA decreased the CA activity to a greater extent, but the photosynthesis rate was higher than in untreated plants, apparently due to an increase in the contents of chlorophylls and carotenoids and stomatal conductivity. It was concluded that SA is involved in the protective and adaptive responses of wheat plants to excess environmental zinc along with other nonhormonal factors and hormones.

Effect of Methyl Jasmonate on the Gene Expression, Encoding Non-Protein Thiol Enzymes in Wheat under Cadmium.

The effect of the phytohormone methyl jasmonate (MJ) on the expression of the TaGS1 and TaPCS1 genes encoding glutathione synthetase and phytochelatin synthase, respectively, which are key enzymes in the synthesis of glutathione and phytochelatins in wheat (cv. Moskovskaya 39), was studied. It was shown for the first time that pretreatment of plants by exogenous MJ (1 µM) leads to an increase in the accumulation of transcripts of the TaGS1 and TaPCS1 genes in leaves without cadmium effect. When cadmium (CdSO4, 100 µM) was added into the nutrient solution, the transcript level of the TaGS1 gene in the plants pretreated by MJ increased (compared to the untreated plants), whereas the transcript level of TaPCS1 remained unaffected. The pretreatment of plants with MJ leads to a lower accumulation of cadmium in the roots and leaves of wheat. At the same time, MJ had no effect on the linear growth parameters of plants, but had a positive effect on the accumulation of biomass under cadmium. It was assumed that MJ is involved in plant tolerance to cadmium by increasing the expression of the TaGS1 and TaPCS1 genes and, as a result, enhancing the synthesis of chelating compounds, as well as by reducing the supply of metal ions to plants.

The level of proapoptotic gene transcripts in wheat leaves under high temperature stress.

Under exposure of wheat plants to high temperatures (33, 37, and 43°C), the level of transcripts of the genes encoding proapoptotic proteins-TaMCAII (encodes type II metacaspase) and TaBAX (functional homologue of the CDF1 gene of Arabidopsis thaliana)-in leaf cells increased. This process at temperatures of 37 and 43°C passed ahead of (in the case of TaBAX mRNA) or was accompanied by (in the case of TaMCAII mRNA) the emergence of signs of nucleosomal DNA degradation in leaves. The accumulation of malondialdehyde in the leaves of seedlings exposed to temperatures of 37 and 43°C coincided in time with a change in the TaMCAII gene expression and the emergence of signs of programmed cell death.