Effect of Selenium, Copper and Manganese Nanocomposites in Arabinogalactan Matrix on Potato Colonization by Phytopathogens Clavibacter sepedonicus and Pectobacterium carotovorum

Abstract

The effect of chemically synthesized nanocomposites (NCs) of selenium (Se/AG NC), copper oxide (Cu/AG NC) and manganese hydroxide (Mn/AG NC), based on the natural polymer arabinogalactan (AG), on the processes of growth, development and colonization of potato plants in vitro was studied upon infection with the causative agent of potato blackleg-the Gram-negative bacterium Pectobacterium carotovorum-and the causative agent of ring rot-the Gram-positive bacterium Clavibacter sepedonicus (Cms). It was shown that the infection of potatoes with P. carotovorum reduced the root formation of plants and the concentration of pigments in leaf tissues. The treatment of plants with Cu/AG NC before infection with P. carotovorum stimulated leaf formation and increased the concentration of pigments in them. A similar effect was observed when potatoes were exposed to Mn/AG NC, and an increase in growth and root formation was also observed. The infection of plants with Cms inhibited plant growth. Treatment with each of the NCs mitigated this negative effect of the phytopathogen. At the same time, Se/AG and Mn/AG NCs promoted leaf formation. The Se/AG NC increased the biomass of Cms-infected plants. The treatment of plants with NCs before infection showed a decrease in the intensity of the colonization of plants by bacteria. The Se/AG NC had the maximum effect, which is probably due to its high antioxidant capacity. Thus, the NCs are able to mitigate the negative effects of bacterial phytopathogens on vegetation and the intensity of colonization by these bacteria during the infection of cultivated plants.

Keywords: Clavibacter sepedonicus; Pectobacterium carotovorum; arabinogalactan; colonization; copper; manganese; nanocomposite; potato; selenium.

Figure 1

Effect of the Se/AG NC at different concentrations on the optical density (OD) of the bacterial suspension Cms after 24 h of incubation; ** indicates significant differences (p ≤ 0.01) between the control and treatments with the Se/AG NC according to the Kruskal–Wallis H-test.

Figure 2

Effect of treatment with Cu/AG, Se/AG and Mn/AG NCs on potato growth (height), number of leaves, weight of fresh roots and shoots infected by P. carotovorum. ** p < 0.05 and * p < 0.01—significance levels when compared with infected samples without NCs treatment.

Figure 3

The effect of Cms infestation and Cu/AG, Se/AG and Mn/AG NC treatment on potato plant growth, leaf number, root weight and fresh shoot weight. ** p < 0.05 and * p < 0.01 are significance levels when compared with infected samples without the NC treatment.

Figure 4

The effect of P. carotovorum (a) and Cms (b) infections and Cu/AG, Se/AG and Mn/AG NC treatment on the concentration of chlorophyll a (Ca) and b (Cb) and carotenoids (C car) in potato plant leaf tissues. ** p < 0.05 and * p < 0.01 are significance levels when compared with infected samples without NC treatment, and the P. carotovorum and Cms infections alone were compared with the non-infected control.

Figure 5

The effect of infection with P. carotovorum (a) and Cms (b) in Petri dishes on the aerial parts, stems and roots of the potato plants and treatment with Se/AG, Cu/AG and Mn/AG NCs on the intensity of the colonization of potato plants by these phytopathogens, respectively, measured as a number of colony-forming units (CFUs) of P. carotovorum and Cms in 0.5 mL homogenate. ** p < 0.01—significance level when compared with infected samples without NC treatment.