Arabidopsis Plants Sense Non-self Peptides to Promote Resistance Against Plectosphaerella cucumerina

Abstract

Peptides are important regulators that participate in the modulation of almost every physiological event in plants, including defense. Recently, many of these peptides have been described as defense elicitors, termed phytocytokines, that are released upon pest or pathogen attack, triggering an amplification of plant defenses. However, little is known about peptides sensing and inducing resistance activities in heterologous plants. In the present study, exogenous peptides from solanaceous species, Systemins and HypSys, are sensed and induce resistance to the necrotrophic fungus Plectosphaerella cucumerina in the taxonomically distant species Arabidopsis thaliana. Surprisingly, other peptides from closer taxonomic clades have very little or no effect on plant protection. In vitro bioassays showed that the studied peptides do not have direct antifungal activities, suggesting that they protect the plant through the promotion of the plant immune system. Interestingly, tomato Systemin was able to induce resistance at very low concentrations (0.1 and 1 nM) and displays a maximum threshold being ineffective above at higher concentrations. Here, we show evidence of the possible involvement of the JA-signaling pathway in the Systemin-Induced Resistance (Sys-IR) in Arabidopsis. Additionally, Systemin treated plants display enhanced BAK1 and BIK1 gene expression following infection as well as increased production of ROS after PAMP treatment suggesting that Systemin sensitizes Arabidopsis perception to pathogens and PAMPs.

A Bifunctional Synthetic Peptide With Antimicrobial and Plant Elicitation Properties That Protect Tomato Plants From Bacterial and Fungal Infections

“…The present results are also in agreement with other reports involving flagellin (Zipfel et al, 2004 ; Pastor-Fernández et al, 2020 ). In addition, and as expected, we have found that tomato plants sprayed with SA, JA, or ethylene increased expression of a wide range of defense-related genes, but 10 genes were unique to BP178 challenged plants.…”

Not Only Systemin: Prosystemin Harbors Other Active Regions Able to Protect Tomato Plants

“…The antifungal assay was carried out as already reported ( Pastor-Fernández et al, 2020 ; Molisso et al, 2021 ). A sterile 12-well plate was filled with potato dextrose broth (PDB 1/2) medium, containing ProSys fragments at the final concentration of 100 fM.…”

Combination of the Systemin peptide with the beneficial fungus Trichoderma afroharzianum T22 improves plant defense responses against pests and diseases

“…To assess if Sys had a direct antimicrobial effect on T. afroharzianum T22 , an in vitro assay was carried out to measure fungal growth in presence or absence of different concentrations of the peptide. Antifungal assays were conducted as previously described (Pastor-Fernández et al, 2020). Wells of a sterile 12-well plate were filled with 1 ml of half-strength potato dextrose broth (PDB 1/2) medium containing Sys, at a final concentration of 100 pM or 100 fM except for the negative control wells.…”

“…Antifungal assays were conducted as previously described (Pastor-Fernández et al, 2020). Wells of a sterile 12-well plate were filled with 1 ml of half-strength potato dextrose broth (PDB 1/2) medium containing Sys, at a final concentration of 100 pM or 100 fM except for the negative control wells.…”