Herrera Diaz A, Kovacs I, Lindermayr C.

PLoS One. 2016 Oct 5;11(10):e0164097. doi: 10.1371/journal.pone.0164097. eCollection 2016.

Abstract

Antimicrobial peptides (AMPs) are small peptides with less than 50 amino acids and are part of the innate immune response in almost all organisms, including bacteria, vertebrates, invertebrates and plants. AMPs are active against a broad-spectrum of pathogens. The inducible expression of AMPs in plants is a promising approach to combat plant pathogens with minimal negative side effects, such as phytotoxicity or infertility. In this study, inducible expression of the de-novo designed AMP SP1-1 in Micro Tom tomato protected tomato fruits against bacterial spot disease caused by Xanthomonas campestris pv. vesicatoria. The peptide SP1-1 was targeted to the apoplast which is the primary infection site for plant pathogens, by fusing SP1-1 peptide to the signal peptide RsAFP1 of radish (Raphanus sativus). The pathogen inducibility of the expression was enabled by using an optimized inducible 4XW2/4XS promoter. As a result, the tomato fruits of independently generated SP1-1 transgenic lines were significantly more resistant to X. campestris pv. vesicatoria than WT tomato fruits. In transgenic lines, bacterial infection was reduced up to 65% in comparison to the infection of WT plants. Our study demonstrates that the combination of the 4XW2/4XS cis-element from parsley with the synthetic antimicrobial peptide SP1-1 is a good alternative to protect tomato fruits against infections with X. campestris pv. vesicatoria.

See: https://www.ncbi.nlm.nih.gov/pubmed/27706237

Fig 1. Antibacterial activity of synthetic peptide SP1-1 in the presence of tomato apoplastic fluid.

X. campestris pv vesicatoria (10⁵ cfu/ml) was incubated with 0 or 10 μg/ml of peptide SP1-1 in the presence or absence of 10 μg/ml of tomato apoplastic fluid. Bacterial growth was determined by measuring OD_600nm (OD 0.2 = 10⁸ cfu/ml) 15 hours after APO; tomato apoplastic fluid. Values represent the mean of at least three biological replicates ± standard error of the mean. Asterisks indicate significant different in comparison to the corresponding control treatment, *P<0.05, **P<0.01.