Botrytis cinerea is a fungal phytopathogen with the second largest worldwide impact on the agricultural industry. We evaluated the ability of four peptides from vertebrate cathelicidins to reduce B. cinerea infection in tomato leaves: two proline-rich peptides (LV-RR32 and TT-FR28) and two α-helix (AM-RV28 and TO-KL37). For this purpose, we inoculated four-week-old tomatoes third leaf with a 5 μL droplet of B. cinerea (2X105 conidia/mL) mixed with each peptide a different concentration (200, 100, 50 and 25 μM). After three days of incubation at 24ºC in dark conditions, the average lesion diameter was determined. From the proline-rich peptides examined, the results showed that LV-RR32 was the most effective, fully inhibiting the infection at 100 μM and greatly reducing it at the lowest concentration. TT-FR28, on the other hand, displayed less activity. The larger size and higher proline and arginine content could be responsible of the higher activity of LV-RR32. In the case of α-helices peptides, AM-RV28 inhibited completely the infection at 100 μM and showed good activity at lower concentrations. Meanwhile, TO-KL37 only reduced the infection at the higher concentration tested (200 μM). In this case, AM-RV28 presented the higher hydrophobicity in its α-helix, which could be related with its higher activity against this fungus.

This study is an important step toward harnessing the power of natural defense molecules to address agricultural challenges, and it lays the groundwork for further exploration of the potential of these peptides for crop protection and pathogen management.