Peptide Fraction Inhibiting Plant Pathogen Growth Predominated in Cell Wall Extracts from Young Plants or in Soluble Cell Fraction from Expanded leaves from Eggplants

Some varieties of eggplant are little susceptible to some plant pathogens, and antimicrobial peptides (AMPs) could be part of this innate-defence mechanism. This work aimed to evaluate the in vitro antimicrobial activity of peptide-enriched fractions from cell wall extracts (CWE) and soluble extracts (SE) from young plants and fully expanded leaves of eggplants against Ralstonia solanacearum and Clavibacter michiganensis ssp. michiganensis growth. The results indicated that the highest inhibition level of the multiplication of both bacteria was obtained with CWE from 5-cm-height plants, while SE promoted the highest inhibition rate when 15-cm-height plants or fully expanded leaves were analysed. These results suggest that young plants exhibit an innate-defence mechanism, very likely involving cell wall AMPs action to minimize plant antimicrobial invasion, while expanded leaves could produce soluble defence molecules. The inhibition rate was dependent for the extract concentration and the extracts were more effective against the growth of Gram-negative bacteria