Lilium Gray Mold Suppression Conferred by the Host Antimicrobial Protein LsGRP1 Involves Main Pathogen-Targeted Manipulation of the Nonantimicrobial Region LsGRP1 N .

Antimicrobial protein LsGRP1 protects Lilium from gray mold mainly caused by the destructive pathogen Botrytis elliptica ; however, its nonantimicrobial region LsGRP1 ^N conversely promotes spore germination of this fungus. By assaying the effects of LsGRP1 ^N , LsGRP1, and the combination of LsGRP1 ^N and the antimicrobial region LsGRP1 ^C on fungal spore germination, hyphal growth, and Lilium gray mold development, LsGRP1 ^N was found to improve the LsGRP1 ^C sensitivity of B. elliptica and disease suppression by LsGRP1 ^C . B. elliptica cell vitality assays indicated that LsGRP1 ^N pretreatment uniquely enhanced the lethal efficiency of LsGRP1 ^C compared to the control peptides. In addition, LsGRP1 ^N -treated B. elliptica was demonstrated to lower infection-related gene expression and increase host-defense-eliciting activity, as indicated by reverse transcription quantitative polymerase chain reaction and histochemical-staining-based callose detection results, respectively. Therefore, LsGRP1 ^N showed a novel mode of action for antimicrobial proteins by manipulating the main pathogen, which facilitated the development of target-specific and dormant microbe-eradicating antimicrobial agents.