Novel Nanobiocomposites Based on Natural Polysaccharides as Universal Trophic Low-Dose Micronutrients.

New promising manganese-containing nanobiocomposites (NCs) based on natural polysaccharides, arabinogalactan (AG), arabinogalactan sulfate (AGS), and κ-carrageenan (κ-CG) were studied to develop novel multi-purpose trophic low-dose organomineral fertilizers. The general toxicological effects of manganese (Mn) on the vegetation of potatoes (Solanum tuberosum L.) was evaluated in this study. The essential physicochemical properties of this trace element in plant tissues, such as its elemental analysis and its spectroscopic parameters in electron paramagnetic resonance (EPR), were determined. Potato plants grown in an NC-containing medium demonstrated better biometric parameters than in the control medium, and no Mn accumulated in plant tissues. In addition, the synthesized NCs demonstrated a pronounced antibacterial effect against the phytopathogenic bacterium Clavibacter sepedonicus (Cms) and were proved to be safe for natural soil microflora.

Antibacterial activity of Calendula officinalis and Echinacea purpurea extracts against the causal agent of tomatoes' bacterial canker: Clavibacter michiganensis subsp. michiganensis / Actividad antibacteriana de los extractos de Calendula officinalis y Echinacea purpurea contra el agente causal del cancro bacteriano del tomate: Clavibacter michiganensis subsp. Michiganensis

We aimed to investigate the effects of Calendula officinalis and Echinacea purpurea extracts in terms of growth parameters, antibacterial activity and phenolic profile in tomato infected by Clavibacter michiganensis subsp. michiganensis (CmmT7). A significant difference was observed in E. purpuraextract, indicating the highest effects on plant height (27.25 cm), fresh plant weight (28.45 cm), root length (24.42 cm), and root weight (6.74 g) (p<0.05). Moreover, Calendula officinalis and Echinacea purpurea extracts showed significant inhibitory activity against CmmT7 (p<0.05). Among phenolic compounds, the only chlorogenic acid amounts were varied in the tomato seedlings leaves with C. officinalis extract (K3) + CmmT7, E. purpurea extract (E3) + CmmT7 and CmmT7 (p<0.01). Moreover, chlorogenic acid amount was approximately 9 times higher than in CmmT7-treated leaves when compared to control. The results showed that application of the extracts of these plants had a significant influence on bacterial canker and growth parameters.

Nuestro objetivo fue investigar los efectos de los extractos de Calendula officinalis y Echinacea purpurea en términos de parámetros de crecimiento, actividad antibacteriana y perfil fenólico en tomate infectado por Clavibacter michiganensis subsp. michiganensis (CmmT7). Se observó una diferencia significativa en el extracto de E. purpura, que indica los mayores efectos sobre la altura de la planta (27,25 cm), el peso de la planta fresca(28,45 cm), la longitud de la raíz (24,42 cm) y el peso de la raíz (6,74 g) (p<0,05). Además, los extractos de Calendula officinalis y Echinacea purpurea mostraron una actividad inhibidora significativa contra CmmT7 (p<0,05). Entre los compuestos fenólicos, las únicas cantidades de ácido clorogénico se variaron en las hojas de las plántulas de tomate con extracto de C. officinalis (K3) CmmT7, extracto de E. purpurea(E3) CmmT7 y CmmT7 (p<0.01). Además, la cantidad de ácido clorogénico fue aproximadamente 9 veces mayor que en las hojas tratadas con CmmT7 en comparación con el control. Los resultados mostraron que la aplicación de los extractos de estas plantas tuvo una influencia significativa sobre el cancro bacteriano y los parámetros de crecimiento.

Selenium Nanocomposites in Natural Matrices as Potato Recovery Agent.

The paper presents a study of the effect of chemically synthesized selenium nanocomposites (Se NCs) in natural polymer matrices arabinogalactan (AG) and starch (ST) on the viability of the potato ring rot pathogen Clavibacter sepedonicus (Cms), potato plants in vitro, and the soil bacterium Rhodococcus erythropolis. It was found that the studied Se NCs have an antibacterial effect against the phytopathogenic Cms, reducing its growth rate and ability to form biofilms. It was revealed that Se NC based on AG (Se/AG NC) stimulated the growth and development of potato plants in vitro as well as their root formation. At the same time, Se did not accumulate in potato tissues after the treatment of plants with Se NCs. The safety of the Se NCs was also confirmed by the absence of a negative effect on the growth and biofilm formation of the soil bacterium R. erythropolis. The obtained results indicate that Se NCs are promising environmentally safe agents for the protection and recovery of cultivated plants from phytopathogenic bacteria.

Plant-produced bacteriocins inhibit plant pathogens and confer disease resistance in tomato.

Bacteriocins are a diverse group of bacterial antimicrobial peptides (AMPs) that represent potential replacements for current antibiotics due to their novel modes of action. At present, production costs are a key constraint to the use of bacteriocins and other AMPs. Here, we report the production of bacteriocins in planta - a potentially scalable and cost-effective approach for AMP production. Nine bacteriocin genes with three different modes of action and minimal or no post-translational modifications were synthesized, cloned and used to transform Arabidopsis thaliana. To confirm bacteriocin functionality and the potential to use these plants as biofactories, Arabidopsis T3 crude leaf extracts were subjected to inhibition assays against the bacterial pathogens Clavibacter michiganensis subsp. michiganensis (Cmm) and Pseudomonas syringae pv. tomato DC3000 (Pst). Six and seven of nine extracts significantly inhibited Cmm and Pst, respectively. Three bacteriocin genes (plantaricin, enteriocin, and leucocin) were then selected for over-expression in tomato (Solanum lycopersicum). In vitro plant pathogen inhibition assays of T0, T1 and T2 transgenic tomato leaf extracts confirmed antimicrobial activity against both pathogens for all three generations of plants, indicating their potential use as stable biopesticide biofactories. Plantaricin and leucocin-expressing T2 tomato plants were resistant to Cmm, and leucocin-expressing T2 plants were resistant to Pst. This study highlights that plants can be used as biofactories for AMP production and that the expression of bacteriocins in planta may offer new opportunities for disease control in agriculture.