The plant pathogen Pantoea ananatis produces N-acylhomoserine lactone and causes center rot disease of onion by quorum sensing.
A number of gram-negative bacteria have a quorum-sensing system and produce N-acyl-l-homoserine lactone (AHL) that they use them as a quorum-sensing signal molecule. Pantoea ananatis is reported as a common colonist of wheat heads at ripening and causes center rot of onion. In this study, we demonstrated that P. ananatis SK-1 produced two AHLs, N-hexanoyl-l-homoserine lactone (C6-HSL) and N-(3-oxohexanoyl)-l-homoserine lactone (3-oxo-C6-HSL). We cloned the AHL-synthase gene (eanI) and AHL-receptor gene (eanR) and revealed that the deduced amino acid sequence of EanI/EanR showed high identity to those of EsaI/EsaR from P. stewartii. EanR repressed the ean box sequence and the addition of AHLs resulted in derepression of ean box. Inactivation of the chromosomal eanI gene in SK-1 caused disruption of exopolysaccharide (EPS) biosynthesis, biofilm formation, and infection of onion leaves, which were recovered by adding exogenous 3-oxo-C6-HSL. These results demonstrated that the quorum-sensing system involved the biosynthesis of EPS, biofilm formation, and infection of onion leaves in P. ananatis SK-1.
Morohoshi
Tomohiro
T
Department of Applied Chemistry, Utsunomiya University, Tochigi 321-8585, Japan. morohosi@cc.utsunomiya-u.ac.jp
Nakamura
Yuta
Y
Yamazaki
Go
G
Ishida
Akio
A
Kato
Norihiro
N
Ikeda
Tsukasa
T
D054742:Acyl-Butyrolactones / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D019697:Onions / Q000382:microbiology*; D020636:Pantoea / Q000235:genetics / Q000378:metabolism*; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D053038:Quorum Sensing / Q000502:physiology*