Seed priming with Pseudomonas putida isolated from rhizosphere triggers innate resistance against Fusarium wilt in tomato through pathogenesis-related protein activation and phenylpropanoid pathway

Pathogenesis-related(PR)proteins are one of the major and preliminary proteins accumulated as a defense against biotic stress.This defense response can be induced by using beneficial rhizobacteria,which has been studied in various host-pathogen interactions.In the present study,eleven Pseudomonas isolates were assessed for their potential to ferment sorbitol,reduce nitrate,and produce mycolytic enzymes,1-aminocyclopropane-l-carboxylic acid(ACC)deaminase,phenazine antibiotics,and N-acyl homoserine lactones(AHLs).All isolates were tested against the host-specific pathogen Fusarium oxysporum MTCC1755 in tomato under greenhouse conditions,and shortlisted isolates were tested for their rhizosphere competence.In-vitro test results showed that the isolates were able to produce mycolytic enzymes,including protease,lipase,chitinase,cellulase,and amylase,and the antibiotic phenazine and were negative for pyoluteorin.All the isolates except two were positive for ACC deaminase production.Greenhouse results showed that the isolates M80,M96,and T109 significantly reduced symptoms of Fusarium wilt.Extended greenhouse tests under autoclaved and unautoclaved soil conditions showed that M80,M96,and T109 were excellent rhizosphere competitors and were identified as Pseudomonas putida.In brief,the defense-specific biochemical variations in the host could describe the improved defense against Fusarium wilt occurring in the primed plants.These three Pseudomonas strains could be used as potential biocontrol agents,along with their rhizosphere competence.

Comparison of cauliflower-insect-fungus interactions and pesticides for cabbage root fly control

Cabbage root fly （Delia radicum L.） control represents a major challenge in brassica production, therefore different management strategies for its control were tested in conventionally managed open field cauliflower production. Strategies included treatments with low-risk methods such as nitrogen lime, the insecticide spinosad and the Beauveria bassiana ATCC 74040-based biopesticide Naturalis. Their effects were compared with treatments based on nonformulated fungal species Metarhizium brunneum, B. bassiana, Clonostachys solani, Trichoderma atroviride, T. koningiopsis, and T. gamsii and commercial insecticides λ-cyhalothrin and thiamethoxam. Spinosad and thiamethoxam were pipetted to individual plants before transplanting; λ-cyhalothrin was sprayed after transplanting; nitrogen lime was applied at first hoeing. Nonformulated fimgi were delivered onto cauliflower plantlets＇ roots as a single pretransplantation inoculation. The cabbage root fly population dynamics exhibited a strong spatiotemporal variation. The lowest number of cabbage root fly pupae recovered from cauliflower roots in the field experiments was recorded in plants treated with spinosad （significant reduction）, followed by Naturalis and one of the tested M. brunneurn strains （nonsignificant reduction）. Significantly more pupae were counted in the nitrogen lime treatment. The field experiments showed that a single drench of cauliflower plantlets with spinosad offered consistent and enduring cabbage root fly control. Naturalis and nonformulated fungal isolates did not decrease cabbage root fly pressure significantly, apparently due to lack of statistical power. The implications of the substantial intra- and inter-annual pest pressure variation and the benefits of using single plant treatments are discussed, and recommendations for improvement of rhizosphere-competence utilizing biological control strategies provided.