Basidiomycetes Polysaccharides Regulate Growth and Antioxidant Defense System in Wheat

Abstract

Higher-fungi xylotrophic basidiomycetes are known to be the reservoirs of bioactive metabolites. Currently, a great deal of attention has been paid to the exploitation of mycelial fungi products as an innovative alternative in crop protection. No data exist on the mechanisms behind the interaction between xylotrophic mushrooms' glycopolymeric substances and plants. In this study, the effects of basidiomycete metabolites on the morphophysiological and biochemical variables of wheat plants have been explored. Wheat (Triticum aestivum L. cv. Saratovskaya 29) seedlings were treated with extracellular polysaccharides (EPSs) isolated from the submerged cultures of twenty basidiomycete strains assigned to 13 species and 8 genera. The EPS solutions at final concentrations of 15, 40, and 80 mg/L were applied to wheat seedlings followed by their growth for 10 days. In the plant samples, the biomass, length of coleoptile, shoot and root, root number, rate of lipid peroxidation by malondialdehyde concentration, content of hydrogen peroxide, and total phenols were measured. The peroxidase and superoxide dismutase activity were defined. Most of the EPS preparations improved biomass yields, as well as the morphological parameters examined. EPS application enhanced the activities of antioxidant enzymes and decreased oxidative damage to lipids. Judging by its overall effect on the growth indices and redox system of wheat plants, an EPS concentration of 40 mg/L has been shown to be the most beneficial compared to other concentrations. This study proves that novel bioformulations based on mushroom EPSs can be developed and are effective for wheat growth and antioxidative response. Phytostimulating properties found for EPSs give grounds to consider extracellular metabolites produced in the xylotrophic basidiomycete cultures as an active component capable of inducing plant responses to stress.

Keywords: Triticum aestivum L.; antioxidant defense; exogenous substances; fungal exopolysaccharides; growth-stimulating effect; higher fungi; mushrooms; natural polymers; wheat plants; xylotrophic basidiomycetes.

Figure 1

Relative fresh weight values in 10-day-old wheat seedlings exposed to fungal preparations. Values are means ± SD; * p ≤ 0,05; ** p ≤ 0.005; *** p ≤ 0.0005; **** p < 0.0001.

Figure 2

Relative MDA values in 10-day-old wheat seedlings exposed to fungal preparations. Values are means ± SD; * p ≤ 0,05; ** p ≤ 0.005; *** p ≤ 0.0005; **** p < 0.0001.

Figure 3

Relative total phenol content values in 10-day-old wheat seedlings exposed to fungal preparations. Values are means ± SD; * p ≤ 0,05; ** p ≤ 0.005; *** p ≤ 0.0005; **** p < 0.0001.

Figure 4

Relative hydrogen peroxide level values in 10-day-old wheat seedlings exposed to fungal preparations. Values are means ± SD; * p ≤ 0,05; ** p ≤ 0.005; *** p ≤ 0.0005; **** p < 0.0001.

Figure 5

Relative peroxidase activity values in 10-day-old wheat seedlings exposed to fungal preparations. Values are means ± SD; ** p ≤ 0.005; **** p < 0.0001.

Figure 6

Relative superoxide dismutase activity values in 10-day-old wheat seedlings exposed to fungal preparations. Values are means ± SD; * p ≤ 0,05; ** p ≤ 0.005; *** p ≤ 0.0005; **** p < 0.0001.