Effectiveness of a Peptide-rich Fraction from <i>Xenorhabdus budapestensis</i> Culture against Fire Blight Disease on Apple Blossoms

Abstract

Erwinia amylovora is one of the most frequently occurred plant pathogenic bacterium. It causes necrosis and blight symptoms on host plants and it lead to considerable yield losses throughout the world on apple trees. There is no effective chemical treatment is currently available against fire blight. The purpose of the present study was to search a new, alternative control method. The evaluation of the plant protection potential of an enriched fraction of Xenorhabdus budapestensis cell-free conditioned media was investigated. Purified samples were tested in vitro and in planta against the phytopathogenic bacterium. A reproducible method for isolation of a peptide-rich fraction from Xenorhabdus cell-free conditioned media was established. The process resulted in 400 mg of dry sample prepared from three litres of Xenorhabdus cell culture. Significant correlation was found between the concentration of the purified preparation and the induced inactivation zones against Erwinia amylovora Ea1 in agar diffusion test method. The minimum inhibitory concentration and minimum bactericidal concentration of the purified fraction against Ea1 strain were 8 μg/mL and 16 μg/mL, respectively. In planta experiments were tested on an apple cultivar ('Watson Jonathan') susceptible to fire blight. The effective range of concentration was 62-200 µg/mL, while treatment with 300 µg/mL and larger amounts caused necrotic symptoms on the petals of flowers. Current study pointed to the effectiveness of the compounds produced by X. budapestensis against fire blight. The development of a commercially applicable formulation of these compounds would allow growers to effectively control fire blight in apple and pear orchards.

Agrobacterium may be used as a suitable experimental system for genetic analysis of resistance to (at least Xenorhabdus budapestensis) antimicrobial peptide complexes

“…The preparation of cell-free conditioned media (CFCM), and obtaining an antimicrobials 353 active peptide-rich fraction (PF) from EMA by using amberlite adsorption followed by 354 methanol (MeOH) elution, as published by ourselves earlier (Furgani et al, 2008;Böszörményi et al, 2009;Vozik et al, 2015). Samples of 10 mg/ml stock solution were kept 356 frozen and then diluted freshly to 1 mg/ml working solutions just before each experiment.…”

“…The lower 411 OD values indicated the stronger antibacterial activity of the EMA PF and higher sensitivity of 412 the Agrobacterium strain tested. Other technical details of the experimental conditions of Liquid 413 Bioassays had been published earlier, (Fodor et al, 2012;Vozik et al, 2015). 414 415 2.…”

Untitled

“…The preparation of cell-free conditioned media (CFCM), and obtaining an antimicrobials 353 active peptide-rich fraction (PF) from EMA by using amberlite adsorption followed by 354 methanol (MeOH) elution, as published by ourselves earlier (Furgani et al, 2008;Böszörményi et al, 2009;Vozik et al, 2015). Samples of 10 mg/ml stock solution were kept 356 frozen and then diluted freshly to 1 mg/ml working solutions just before each experiment.…”

“…The lower 411 OD values indicated the stronger antibacterial activity of the EMA PF and higher sensitivity of 412 the Agrobacterium strain tested. Other technical details of the experimental conditions of Liquid 413 Bioassays had been published earlier, (Fodor et al, 2012;Vozik et al, 2015). 414 415 2.…”

Untitled

“…The preparation of cell-free conditioned media (CFCM), and obtaining an antimicrobials 353 active peptide-rich fraction (PF) from EMA by using amberlite adsorption followed by 354 methanol (MeOH) elution, as published by ourselves earlier (Furgani et al, 2008;Böszörményi et al, 2009;Vozik et al, 2015). Samples of 10 mg/ml stock solution were kept 356 frozen and then diluted freshly to 1 mg/ml working solutions just before each experiment.…”