The elicitor protein BcIEB1 and the derived peptide ieb35 provide long-term plant protection

BcIEB is a small protein secreted by the phytopathogenic fungus Botrytis cinerea that is recognized as a pathogen-associated molecular pattern (PAMP) by plants. This activity is mapped to a highly conserved region of 35 amino acids, the peptide ieb35. Moreover, it has been shown that the protein and the peptide induce systemic resistance to B. cinerea after their infiltration into tobacco leaves. In this work, the possible use of BcIBE1 or ieb35 as plant protective agents has been tested. Tobacco plants were sprayed, infiltrated, or treated at the seedling stage with the protein or the peptide, and plant susceptibility to pathogens with different lifestyles was then studied at various times after treatment. The results showed that both BcIEB1 and ieb35 caused a similar reduction in the lesion sizes caused by B. cinerea and in colonization by Pseudomonas syringae pv. tabaci (reduced by c. 30% and c. 40%, respectively), independently of the treatment type. In addition, the number of B. cinerea inoculations leading to successful infections was also reduced in plants infiltrated or sprayed with BcIEB1/ieb35. The defence-related genes PR1a, NPR1, and osmotin ap24 were all induced by the protein and the peptide. BcIEB1, and especially ieb35, may be considered as a potential environmentally friendly treatment to increase plant resistance to pathogens.