Control of Citrus Post-harvest Green Molds, Blue Molds, and Sour Rot by the Cecropin A-Melittin Hybrid Peptide BP21.

Wenjun Wang,Kaifang Zeng,Jian Ming,Sha Liu,Shixiang Yao,Lili Deng

doi:10.3389/fmicb.2018.02455

Abstract

In this study, the activity of the cecropin A-melittin hybrid peptide BP21 (Ac-FKLFKKILKVL-NH2) in controlling of citrus post-harvest green and blue molds and sour rot and its involved mechanism was studied. The minimum inhibitory concentrations of BP21 against Penicillium digitatum, Penicillium italicum, and Geotrichum candidum were 8, 8, and 4 μmol L-1, respectively. BP21 could inhibit the growth of mycelia, the scanning electron microscopy results clearly showed that the mycelia treated with BP21 shrank, formed a rough surface, became distorted and collapsed. Fluorescent staining with SYTOX Green (SG) indicated that BP21 could disintegrate membranes. Membrane permeability parameters, including extracellular conductivity, the leakage of potassium ions, and the release of cellular constituents, visibly increased as the BP21 concentration increased. Gross and irreversible damage to the cytoplasm and membranes was observed. There was a positive correlation between hemolytic activity and the concentration of BP21. These results suggest peptide BP21 could be used to control citrus post-harvest diseases.

Highlights

Green mold, blue mold, and sour rot caused by Penicillium digitatum, Penicillium Italicum, and Geotrichum candidum
Further antibacterial mode of action of peptide BP21 against the fungi was confirmed using the assay for the extracellular conductance (Figure 4)
The peptide BP21 could increase the extracellular conductivity of P. digitatum, P. italicum, and G. candidum

Summary

Introduction

Blue mold, and sour rot caused by Penicillium digitatum, Penicillium Italicum, and Geotrichum candidum Sour rot cannot be inhibited by imazalil and thiabendazole, which are effective chemical fungicides against green mold and blue mold (Droby et al, 2002; Ismail and Zhang, 2004). It is urgent to search for effective, ecofriendly methods of diseases control to replace or reduce the use of harmful chemical fungicides (Schirra et al, 2011; Romanazzi et al, 2017). The application of peptides in the control of fruit and vegetable diseases is gaining attention. An increasing number of AMPs have been shown to control fruit and vegetable diseases. PAF56 (GHRKKWFW) was shown to effectively control of fungi infection in citrus

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Conclusion