Development of a gum tragacanth-coated nanoparticle system for controlled release of plant extracts against Erwinia amylovora.

Fire blight, caused by Erwinia amylovora, is a significant threat to fruit crops, with limited biocontrol methods. This study aimed to develop a nanosystem using mesoporous silica nanoparticles (MSNs) loaded with a phenolic plant extract (ZP) derived from Myrtus communis, Thymus vulgaris, and Curcuma longa, and coated with natural biopolymers Gum Tragacanth (GT) and sodium alginate (SA). The MSNs were synthesized and characterized by XRD, FTIR, and TEM, exhibiting a specific surface area of about 750 m2/g and an average pore diameter of 5 nm. ZP was effectively loaded into the MSNs with a loading efficiency of ∼25 %, and GT-MSNs-ZP demonstrated sustained release, releasing 56 % of phenolic compounds over 168 h. In antibacterial tests, GT-MSNs-ZP demonstrated the highest effectiveness against E. amylovora, maintaining inhibition for up to 7 days. In vivo experiments showed that GT-MSNs-ZP reduced diseased leaves by 60 % at a concentration of 5/1000 mL/mL, comparable to commercial pesticides. Additionally, the system showed no adverse effects on beneficial bacteria such as Rhizobium meliloti and Bacillus licheniformis. These results emphasize the potential of GT-MSNs-ZP as a sustainable and effective biocontrol solution for agricultural applications.