Investigating Cellulose Nanocrystals’ Biocompatibility and Their Effects on Pseudomonas syringae pv. tomato Epiphytic Survival for Sustainable Crop Protection

Abstract

Nanotechnology could play a huge role in ensuring safer and greener agriculture in the years ahead by providing sustainable tools to control plant diseases. In this study, the possibility of using cellulose nanocrystals (CNCs) obtained from tomato waste to control the bacterial speck disease’s causal agent was evaluated for the effects on plant development. Biocompatibility was assessed by studying seeds’ germination, leaf area, biomass and nitrogen balance index of tomato seedlings treated with CNC. Since epiphytic survival represents a relevant phase in early and later infections provoked by Pseudomonas syringae pv. tomato (Pst), the CNC’s ability to lower the level of bacterial cells in the plant canopy was evaluated in treated seedlings at 1, 7 and 14 days after being artificially inoculated. Leaflets were collected and washed to quantify the epiphytic bacterial population and observed through electron microscopy. Obtained results indicate that CNCs are non-toxic, compatible nanomaterials, highlighting at the same time their potential in counteracting bacterial speck disease by decreasing the level of epiphytic population after two weeks from inoculation by up to one log unit (3.08 CFU cm−2) compared to the control (3.94 CFU cm−2). Moreover, we were able to demonstrate that it is possible to cut in half the amount of copper without losing effectiveness in controlling the bacteria by mixing it with CNCs, concluding that CNCs could be used to design innovative sustainable plant protection strategies.