Title Effect of WGA on 24-Epibrassinolide-Induced Resistance of Wheat Plants and Cell Walls Reinforcement under the Influence of Cadmium Acetate

The generally accepted approach for increasing plant resistance to heavy metals is the treatment by phytohormones of different natures. In particular, brassinosteroids are highly effective in decreasing the level of toxic ions damage effects on plant growth. ABA and wheat germ agglutinin (WGA) contents were measured in the same plant with the help of enzyme immunoassay method. The localization of lignin and suberin on cross sections of wheat roots stained with berberine hemisulfate/toluidine blue was performed. The mitotic index was determined as percentage of mitotic cells of the total number of the cells. It was found that 0.4 μM 24-epibrassinolide (EBR) seed pretreatment under the influence of 1 mM cadmium acetate in the presence of fluridone (Fl) inhibited the stress-induced accumulation of ABA, while the WGA content in plants stayed higher than in stressed EBR-untreated wheat roots. Moreover, EBR-pretreated wheat plants under cadmium stress formed in the root cell walls’ Casparian bands and suberin lamellae, which are the critical locations in the apoplastic barriers of endodermis and exodermis. Pre-sowing EBR-treatment promoted acceleration of Casparian bands and suberin lamellae formation without inhibiting growth processes. We have demonstrated the involvement of wheat lectin in the realization of EBR-induced protective effect on plants under cadmium stress. An important contribution to EBR-induced strengthening the barrier properties of the cell walls of the studied tissues is the ability of EBR to induce ABA-independent accumulation of WGA, which further promotes the increasing lignin and suberin biopolymers deposition in the cell walls of wheat roots.