Self-Assembly of a Dipeptide with a Reduced Amount of Copper into Antifungal and Antibacterial Particles

Abstract

With the growing concern over the environmental impact and health risks associated with conventional pesticides, there is a great need for developing safer and more sustainable alternatives. This study demonstrates the self-assembly of antimicrobial and antifungal spherical particles by a dipeptide utilizing a reduced amount of copper salt compared to the commonly employed formulation. The particles can be sprayed on a surface and form an antimicrobial coating. The effectiveness of the coating against the bacteria Pectobacterium brasiliense, a common pathogen affecting potato crops, was demonstrated, as the coating reduced the bacterial load by 7.3 log. Moreover, a comprehensive field trial was conducted, where the formulation was applied to potato seeds. Remarkably, it exhibited good efficacy against three prevalent potato pathogens (P. brasiliense, Pythium spp., and Spongospora subterranea) while demonstrating no phytotoxic effects on the potatoes. These findings highlight the tremendous potential of this formulation as a nonphytotoxic alternative to replace hazardous pesticides currently available in the market. ■ INTRODUCTIONCrop pathogens are a serious concern in the field of agriculture as they cause a threat to the productivity and quality of crop yields. These harmful microorganisms, such as bacteria, viruses, and fungi, can cause devastating diseases in various crops, leading to substantial economic losses and food security issues. 1 Notably, the most consumed crops�wheat, maize, potato, rice, and soybean�face losses ranging from 17 to 30% due to pathogens and pests. 2 Potato crop, being one of the most extensively cultivated crops, is highly susceptible to a range of pathogens that can result in significant loss of harvest. 1,3 Among the common pathogens that pose a severe threat to potatoes are Pectobacterium brasiliense, Pythium spp., and Spongospora subterranea. P. brasiliense is the primary pathogenic factor contributing to the global prevalence of soft rot and blackleg diseases in potato tubers and stems. 4 These bacteria are known to produce large quantities of pectic enzymes, which break down pectin in plant cell walls, leading to cellular damage and collapse. P. brasiliense bacteria are present on plant surfaces and in soil, and they can enter plants through wounds or natural openings like lenticels. 5 They remain in these locations until the environmental conditions�such as the presence of free water, oxygen availability, and appropriate temperature� become favorable to the development of diseases. 5 In addition to bacterial pathogens, fungi are commonly found in soil and water. One prevalent pathogenic fungus found in such an environment is Pythium spp. Once Pythium spp. infects a potato, it causes a condition known as "damping-off" in seedlings, where the young plants collapse and die before or shortly after emergence. In mature plants, Pythium spp. can cause root rot, leading to stunted growth, wilting, and eventual death. 6 Another damaging pathogen is S. subterranea, which causes a signifi...