The genome and genetics of a high oxidative stress tolerant Serratia sp. LCN16 isolated from the plant parasitic nematode Bursaphelenchus xylophilusReport as inadecuate




The genome and genetics of a high oxidative stress tolerant Serratia sp. LCN16 isolated from the plant parasitic nematode Bursaphelenchus xylophilus - Download this document for free, or read online. Document in PDF available to download.

BMC Genomics

, 17:301

Prokaryote microbial genomics

Abstract

BackgroundPine wilt disease PWD is a worldwide threat to pine forests, and is caused by the pine wood nematode PWN Bursaphelenchus xylophilus. Bacteria are known to be associated with PWN and may have an important role in PWD. Serratia sp. LCN16 is a PWN-associated bacterium, highly resistant to oxidative stress in vitro, and which beneficially contributes to the PWN survival under these conditions. Oxidative stress is generated as a part of the basal defense mechanism used by plants to combat pathogenic invasion. Here, we studied the biology of Serratia sp. LCN16 through genome analyses, and further investigated, using reverse genetics, the role of two genes directly involved in the neutralization of H2O2, namely the H2O2 transcriptional factor oxyR; and the H2O2-targeting enzyme, catalase katA.

ResultsSerratia sp. LCN16 is phylogenetically most closely related to the phytosphere group of Serratia, which includes S. proteamaculans, S. grimessi and S. liquefaciens. Likewise, Serratia sp. LCN16 shares many features with endophytes plant-associated bacteria, such as genes coding for plant polymer degrading enzymes, iron uptake-transport, siderophore and phytohormone synthesis, aromatic compound degradation and detoxification enzymes. OxyR and KatA are directly involved in the high tolerance to H2O2 of Serratia sp. LCN16. Under oxidative stress, Serratia sp. LCN16 expresses katA independently of OxyR in contrast with katG which is under positive regulation of OxyR. Serratia sp. LCN16 mutants for oxyR oxyR::int614 and katA katA::int808 were sensitive to H2O2 in relation with wild-type, and both failed to protect the PWN from H2O2-stress exposure. Moreover, both mutants showed different phenotypes in terms of biofilm production and swimming-swarming behaviors.

ConclusionsThis study provides new insights into the biology of PWN-associated bacteria Serratia sp. LCN16 and its extreme resistance to oxidative stress conditions, encouraging further research on the potential role of this bacterium in interaction with PWN in planta environment.

KeywordsBursaphelenchus xylophilus Catalase Endophyte Reactive oxygen species OxyR Serratia Oxidative stress Pine wilt disease Plant defenses AbbreviationsCDScoding sequences

CFUcolony forming unit

CRISPRclustered regularly interspaced short palindromic repeats

GIgenomic islands

GOgene ontology

GPXglutathione peroxidase

GSTgluthathione S-transferase

H2O2hydrogen peroxide

IAAindole acetic acid

KATcatalase

MGEmobile genomic elements

PRXperoxiredoxin

PWDpine wilt disease

PWNpine wood nematode

ROSreactive oxygen species

SODsuperoxidase dismutase

TPXthiol peroxidase

TRXthioredoxin

WTwild type

Electronic supplementary materialThe online version of this article doi:10.1186-s12864-016-2626-1 contains supplementary material, which is available to authorized users.

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Author: Claudia S. L. Vicente - Francisco X. Nascimento - Yoriko Ikuyo - Peter J. A. Cock - Manuel Mota - Koichi Hasegawa

Source: https://link.springer.com/







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