ABSTRACT
The role of endophytic communities of seeds is still poorly characterised. The purpose of this work was to survey the presence of bacterial endophytes in the seeds of a commercial wheat cultivar widely sown in Argentina and to look for plant growth promotion features and biocontrol abilities against Fusarium graminearum among them. Six isolates were obtained from wheat seeds following a culture-dependent protocol. Four isolates were assignated to Paenibacillus genus according to their 16S rRNA sequencing. The only gammaproteobacteria isolated, presumably an Enterobactereaceae of Pantoea genus, was particularly active as IAA and siderophore producer, and also solubilised phosphate and was the only one that grew on N-free medium. Several of these isolates demonstrated ability to restrain F. graminearum growth on dual culture and in a bioassay using barley and wheat kernels. An outstanding ability to form biofilm on an inert surface was corroborated for those Paenibacillus which displayed greater biocontrol of F. graminearum, and the inoculation with one of these isolates in combination with the Pantoea isolate resulted in greater chlorophyll content in barley seedlings. Our results show a significant ecological potential of some components of the wheat seed endophytic community.
Subject(s)
Antibiosis , Bacteria/isolation & purification , Endophytes/isolation & purification , Fusarium/growth & development , Plant Growth Regulators/metabolism , Seeds/microbiology , Triticum/microbiology , Argentina , Bacteria/classification , Bacteria/growth & development , Bacteria/metabolism , Biofilms/growth & development , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , DNA, Ribosomal/chemistry , DNA, Ribosomal/genetics , Endophytes/classification , Endophytes/growth & development , Endophytes/metabolism , Hordeum/microbiology , Indoleacetic Acids/metabolism , Phosphates/metabolism , Promoter Regions, Genetic , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNA , Siderophores/metabolismABSTRACT
Eight endophytic isolates assigned to Pseudomonas, Azospirillum, and Bacillus genera according to pheno-genotypic features were retrieved from barley seeds under selective pressure for nitrogen-fixers. Genetic relationships among related isolates were investigated through RAPD. Six isolates displayed nitrogen-fixing ability, while all could biosynthesize indolacetic acid in vitro and showed no antibiosis effects against Azospirillum brasilense Az39, a recognized PGPR.
Subject(s)
Azospirillum brasilense/isolation & purification , Bacillus/isolation & purification , Endophytes/isolation & purification , Hordeum/microbiology , Nitrogen Fixation , Pseudomonas/isolation & purification , Seeds/microbiology , Antibiosis , Azospirillum brasilense/classification , Azospirillum brasilense/genetics , Azospirillum brasilense/metabolism , Bacillus/classification , Bacillus/genetics , Bacillus/metabolism , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , DNA, Ribosomal/chemistry , DNA, Ribosomal/genetics , Endophytes/classification , Endophytes/genetics , Endophytes/metabolism , Indoleacetic Acids/metabolism , Molecular Typing , Pseudomonas/classification , Pseudomonas/genetics , Pseudomonas/metabolism , RNA, Ribosomal, 16S/genetics , Random Amplified Polymorphic DNA Technique , Sequence Analysis, DNAABSTRACT
Eight endophytic isolates assigned to Pseudomonas, Azospirillum, and Bacillus genera according to pheno-genotypic features were retrieved from barley seeds under selective pressure for nitrogen-fixers. Genetic relationships among related isolates were investigated through RAPD. Six isolates displayed nitrogen-fixing ability, while all could biosynthesize indolacetic acid in vitro and showed no antibiosis effects against Azospirillum brasilense Az39, a recognized PGPR.
