s " Trichoderma and Pseudomonas strains were isolated from cucumber rhizosphere. " Strains were tested for eliciting systemic resistance against Fusarium in cucumber. " Combining Trichoderma and Pseudomonas leads to enhanced induced resistance. " This enhanced effectiveness is observed in cucumber but not in Arabidopsis. " In cucumber the enhanced effectiveness is paralleled by enhanced priming of defense genes.

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Summary Endophytic bacteria of rice plants (Oryza sativa L.) from eight diff erent cultivars were screened for their ability in inducing disease symptoms, plant growth promotion and antagonistic activity against Xanthomonas oryzae pv. oryzae. Out of the 63 whole isolates, fi ve were plant pathogens. Based on phenotypic characteristics and 16S rDNA sequence analysis, these were identified as Pseudomonas oryzihabitans, P. fulva, Pantoea ananatis, Pantoea sp., Cellulomonas sp. Four out of the 63 isolates behaved as potentially good plant growth-promoting and biocontrol agents. These were identifi ed as Bacillus sp., B. subtilis, Pseudomonas putida and Enterobacter sp. This is the fi rst report of pathogenic and endophytic bacteria from rice grown in fi eld conditions in North of Iran.

The serious wheat pathogen Fusarium graminearum causes both root rot and head blight. Some classical biocontrol tests were first used to explore the biocontrol ability of 39 Pseudomonas fluorescens strains. The five most antifungal strains B4, P13, UTPf127, UTPf125 and UTPf105 were selected to screen known antifungal antibiotic genes and greenhouse experiments. The ability of bacteria to colonize wheat rhizosphere and their effect on plant growth in the presence and absence of soil F. graminearum inoculum was studied under greenhouse conditions. Overall, biocontrol bacteria populations were significantly higher in both wheat endo‐and ectorhizosphere of pathogen‐inoculated soil than in healthy soil. The population of all strains differently decreased with time. On day 28, endorhizosphere populations of strain B4 could be detected in inoculated but not healthy soil, while UTPf127 populations remained high in endorhizospheres at all tested times. Isolate B4 and UTPf105 showed the most substantial plant growth in pathogen‐inoculated soil compared to pathogen‐inoculated soil without added bacteria. UTPf127‐treated plants grew better in control soil than when the pathogen was present. In contrast, UTPf125 and P13 showed little effect on plant growth. These results point to complex interactions between pathogen and biocontrol bacteria and suggest that a fungal pathogen in the soil can affect the survival of potential bacterial biological control agents. Additionally, they highlight the importance of screening and evaluating potential biocontrol bacteria against soilborne fungal pathogens by in vivo tests rather than relying on plate screenings.

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