Author: FERNANDO ZAMUDIO ZUÑIGA
Habanero chili pepper (Capsicum chinense) is widely consumed as a fresh vegetable, although its extremely high capsaicin content has led to other uses (e.g., medicine and self-defense). Recently described antimicrobial peptides from C. annuum were very efficient in inhibiting growth in human and plant pathogenic bacteria and fungi. In order to explore the potential use of Capsicum chinenseseeds as a source of antimicrobial peptides, in the present study a peptide fraction from C. chinense pepper seeds, denominated G10P1, was enriched, partially purified and its antimicrobial activitytested against the plant and human pathogens Xanthomonas campestris, Pseudomonas syringae, Pseudomonas aeruginosa, Erwinia carotovora, Agrobacterium sp., Shigella flexnerii, Escherichia coli, Staphyllococcus aureus and Bacillus subtilis. The minimum inhibitory concentration of the G10P1 peptide fraction against X. campestris was 12.5 μg mL-1. Electrophoresis of the G10P1 in a denaturant 15% polyacrylamide gel showed it to be composed of ~7.57 and ~5.6 kDa polypeptides, both associated with an area of strong antibacterial activity. The sequencing of 18 amino acids from the N-terminal of the ~7.57 peptides and 12 from the ~5.6 kDa peptides showed no clear association with previously described antimicrobial peptides. However, the ~5.6 kDa peptides were related to the NAC and WRKY transcription factors, both involved in direct regulation of the plant defense response against pathogen attack and the ~7.57 kDa peptides had low homology with a 3-oxo-[acyl-carrier-protein] synthase from Capsicum chinense.