Each trial was repeated at least twice with at least three replicates for each treatment. Nucleotide sequence accession numbers The GenBank accession numbers for the splIR, and spsRI genes from strain G3 are FJ919305 and FJ919306, respectively. Results Phylogenetic classification of S. plymuthica G3 To classify phylogenetically the G3 strain isolated from wheat stems, the sequence from the 1474-bp fragment of 16S rDNA from this isolate we previously determined (EU344964) [23] was subjected to phylogenetic analysis with different 16S rDNA sequences from members of the genus Serratia and E. coli strain ATCC 25922 as the outgroup. The sequence alignment for the phylogenetic tree

was constructed and evaluated

with MEGA 4 using the neighbour-joining method (see ��-Nicotinamide Additional file 1). As the phylogenetic tree showed that the G3 isolate was clustered within the same group (confidence = 99%) with RVH1 (AY394724) and the type strain DSM 4540 (AJ233433) of S. plymuthica, respectively. Therefore, Serratia sp. G3 was tentatively classified as S. learn more plymuthica. It is worth noting that the atypical S. plymuthica RVH1 strain is unable to produce prodigiosin pigment when compared to the S. plymuthica DSM 4540 type strain, but a combined comparative analysis of 16S rRNA and gyrB sequences, DNA-DNA hybridization, and biochemical characteristics unequivocally identified this strain as S. plymuthica Protein Tyrosine Kinase inhibitor [7]. S. plymuthica G3 possesses two quorum sensing systems SplIR and SpsRI The homologues of the two LuxIR genes

were cloned from strain G3 by PCR using primers against conserved sequences as described in the Material and Methods. PCR products of 1441-bp and 1391-bp corresponding to the expected splIR and spsIR respectively were sequenced. The 1441-bp resulting sequence included two open reading frames (ORFs) corresponding to the predicted AHL synthase gene splI (633-bp) and the response regulator gene splR (750-bp) (FJ919305). The splI and splR ORFs are convergent, overlapping by 29-bp in their 3′ regions. The 1391-bp sequenced fragment carried two ORFs corresponding to the predicted AHL synthase gene spsI (687-bp) and the response regulator gene (spsR) (747-bp) (FJ919306). The spsR and spsI ORFs are also convergent and overlapping by 54-bp in their 3′ regions. Database searches using tblastx revealed that SplI (ACR22886) shares 99% and 98% identity to SplI (AAR32908, AAW27921) from S. plymuthica strains RVH1 and HRO-C48, respectively, as well as 83, 68, 67% identity to the SprI (AAK76733) from Serratia proteamaculans B5a, SpnI (AAN52498) from S. marcescens SS-1, and EsaI (AAA82096) from Pantoea GSK2245840 molecular weight stewartii DC283 respectively, which are mainly responsible for the synthesis of 3-oxo-C6-HSL [15, 16, 33–36]. The second LuxI homolog SpsI from G3 was most similar to the LuxI homolog (ABV39177) from the poplar endophytic bacterium S.