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.

Seed Treatment with Salicylic Acid Increases Gene Expression and Activity of Antioxidant Enzymes in Wheat Plants in Zinc or Copper Deficiency.

The effect of wheat seed treatment with salicylic acid (SA) on expression of the TaCu/ZnSOD, TaFeSOD, and TaCAT2 genes and activities of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in leaves was studied at optimal contents of zinc (2 µM) and copper (0.3 µM) in the root environment and in zinc and copper deficiencies. Seed treatment with SA was for the first time shown to increase of the amount of transcripts of the above genes as compared with untreated plants, both in optimal conditions and in zinc or copper deficiency. Activities of the enzymes, especially catalase, also increased. Judging by the malondialdehyde (MDA) content, the changes make it possible to avoid an increase in lipid peroxidation (LPO) and, therefore, oxidative stress. A positive effect of seed treatment with SA on activities of the main antioxidant enzymes was assumed to underlie the stimulating effect of SA on physiological processes in plants exposed to microelement deficiency.

The HMA2 Gene Expression in Leaves of Introgressive Wheat Lines under Zn Optimum and Deficiency Content in Root Environment.

In two introgressive lines of bread wheat (15-7-1 and 15-7-2), which differ in the allelic status of the Gpc-B1 gene, the expression of the gene encoding the HMA2 transport protein in flag leaves under optimum Zn content in substrate (2 µÐœ) and in its deficiency (0 µÐœ) was investigated. This is the first study to show that the plants carrying functional allele of the Gpc-В1 gene (line 15-7-1) have a higher level of TaHMA2 transcripts than the plants with nonfunctional allele of the Gpc-В1 gene (line 15-7-2) both at optimum Zn content in substrate and at its deficiency. Importantly, the high TaHMA2 gene expression did not affect the wheat shoot growth but correlated with a high Zn concentration in the aboveground part of plants. It is assumed that the NAC transcription factor encoded by the Gpc-В1 gene may be involved in the regulation of the ТаНМА2 gene expression.

Effect of Methyl Jasmonate on the Expression of Wcs Genes and the Activity of Antioxidant Enzymes at Wheat Cold Adaptation.

We studied the effect of phytohormone methyl jasmonate (MJ) on the expression of WCS (wheat cold specific) family genes and the activity of the key antioxidant enzymes in wheat seedling leaves at a low hardening temperature (4°C). Incubation at 4°C induced an increase in the cold tolerance of seedlings, which was accompanied by an increase in the levels of transcripts of WCS120 and WCS19 genes as well as an increase in the activity of superoxide dismutase (SOD) and peroxidase (PO). The pretreatment of seedlings with MJ significantly increased the mRNA content of WCS120 and WCS19 genes and, at the same time, caused an increase in the activity of SOD and PO, thus contributing to further increase in the cold tolerance of the plants (i.e., enhanced the hardening effect induced by low temperature).

The abscisic acid influence on the gene expression of pro- and anti-apoptotic proteins in the leaves of cucumber plants at low temperatures.

We studied the effect of abscisic acid (ABA) on the expression of genes encoding the functional homologues of proapoptotic (CsBAX) and antiapoptotic (CsBI-1) proteins in cucumber leaves at low temperatures. The exposure to a hardening temperature of 12°C caused a slight increase in the level of CsBAX gene transcript and a sharp increase in the CsBI-1 gene transcript. At a damaging temperature of 4°C, the content of the CsBAX gene mRNA significantly increased, whereas the content of the CsBI-1 gene mRNA remained virtually unchanged. The treatment of seedlings with ABA reduced the release of electrolytes from cells and both 12 and 4°C, i.e., increased the cold resistance and simultaneously decreased the level of CsBAX gene transcripts, but drastically increased the content of CsBI-1 gene mRNA.