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vfr, A Global Regulatory Gene, is Required for Pyrrolnitrin but not for Phenazine-1-carboxylic Acid Biosynthesis in Pseudomonas chlororaphis G05
Plant Pathol. J. 2019;35:351-361
Published online August 1, 2019
© 2019 The Korean Society of Plant Pathology.

Xia Wu1†, Xiaoyan Chi1†, Yanhua Wang1†, Kailu Zhang1, Le Kai1, Qiuning He1, Jinxiu Tang1, Kewen Wang1, Longshuo Sun1, Xiuying Hao2, Weihai Xie1* , and Yihe Ge1*

1Department of Applied and Environmental Microbiology, School of Life Sciences, Ludong University, Yantai 264025, China
2Institute of Applied Microbiology, Xinjiang Academy of Agricultural Sciences, Urumqi 830001, China
Correspondence to: Weihai Xie
Phone) +86-535-6681053, FAX) +86-535-6692760
Yihe Ge
Phone) +86-535-6685003, FAX) +86-535-6692726

These authors contributed this work equally.
Received January 16, 2019; Revised April 7, 2019; Accepted April 9, 2019.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
In our previous study, pyrrolnitrin produced in Pseudomonas chlororaphis G05 plays more critical role in suppression of mycelial growth of some fungal pathogens that cause plant diseases in agriculture. Although some regulators for pyrrolnitrin biosynthesis were identified, the pyrrolnitrin regulation pathway was not fully constructed. During our screening novel regulator candidates, we obtained a white conjugant G05W02 while transposon mutagenesis was carried out between a fusion mutant G05∆phzprn::lacZ and E. coli S17-1 (pUT/mini-Tn5Kan). By cloning and sequencing of the transposon-flanking DNA fragment, we found that a vfr gene in the conjugant G05W02 was disrupted with mini-Tn5Kan. In one other previous study on P. fluorescens, however, it was reported that the deletion of the vfr caused increased production of pyrrolnitrin and other antifungal metabolites. To confirm its regulatory function, we constructed the vfr-knockout mutant G05∆vfr and G05∆phzprn::lacZ∆vfr. By quantifying β-galactosidase activities, we found that deletion of the vfr decreased the prn operon expression dramatically. Meanwhile, by quantifying pyrrolnitrin production in the mutant G05∆vfr, we found that deficiency of the Vfr caused decreased pyrrolnitrin production. However, production of phenazine-1-carboxylic acid was same to that in the wild-type strain G05. Taken together, Vfr is required for pyrrolnitrin but not for phenazine-1-carboxylic acid biosynthesis in P. chlororaphis G05.
Keywords : P. chlororaphis, phenazine-1-carboxylic acid, pyrrolnitrin, regulation, Vfr

August 2019, 35 (4)
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