Copper may help reduce the use of antibiotics in crops

A drop of water on a leaf. (Reference image by ju1959jjj, Pixabay).

Researchers at Russia’s National University of Science and Technology MISIS, Voronezh State University of Forestry and Technologies and Tambov State University discovered that copper oxide nanoparticles in the composition of a preparation to protect in-vitro-derived seedlings work as an immunostimulator in plants.

These findings have led the researchers to work on a new preparation that will increase the amount of harvested planting material.

In a paper published in the journal Nanomaterials, the scientists explain that modern methods of mass phytoproduction include obtaining planting material of woody plants by clonal micropropagation in vitro. This method of vegetative propagation makes it possible to obtain new plants, genetically identical to the original specimen, in a laboratory vessel or other controlled experimental environment rather than within a living organism or natural setting.

The technology, however, poses some challenges. As nutrient media for phyto-clones provide ideal conditions for microbial growth, new plants need to be created and maintained in complete sterility. Antibiotics are increasingly being used to reduce the risk of contamination in plants propagated in vitro.

But along with their bactericidal effect, antibiotics can also have a toxic effect on plant tissues and inhibit their growth and development. In addition, microorganisms can adapt to biocidal drugs by mutations, which lead to the resistance of phytopathogens.

Enter copper oxide nanoparticles 

In the view of the Russian experts, thus, using copper nanoparticles as sterilizing agents may be a safe alternative to antibiotics.

Looking specifically at the effects of copper oxide nanoparticles on the growth of colonies of spore-forming mold fungi, as well as on the production of stress-resistant genes in birch clones in vitro when infected with phytopathogens, the group found that copper oxide nanoparticles had a pronounced antifungal effect on phytopathogens in plant culture.

“As possible mechanisms of this phenomenon, we assume both the diffusion of copper ions, which is an antimicrobial agent, and specific nanotoxic effects, such as the induction of oxidative stress or damage to the cell membrane,” Olga Zakharova, one of the study’s co-authors, said in a media statement.

Boosting immunity

According to Zakharova and her colleagues, the maximum sterility of plants was observed at the lowest concentration of nanoparticles studied. Thus, it is possible that the effect is achieved not through the direct destruction of phytopathogenic microorganisms by nanoparticles, but indirectly through the stimulation of immunity of seedlings.

“Nanoparticles in low concentrations can cause moderate stress in plants, one of the reactions to which is a change in their biochemical status,” Zakharova said.

“Compounds such as peroxidases and polyphenols, which are part of the system of non-specific protection of plants against phytopathogenic microorganisms, are beginning to be produced. At the same time, an increase in the concentration of nanoparticles increases the ‘nano’ induced stress, and the overall efficiency of plant adaptation to stress begins to decrease, which is ultimately manifested by a reduced number of viable micro-clones at the maximum concentration of nanoparticles.”

The researcher pointed out that the data they obtained confirm the prospect of using copper oxide nanoparticles to optimize the technology of plant cultivation in vitro.