Soil-borne Verticillium wilt update November 2016

The overall objective of the project is to develop a sustainable method of protecting oilseed rape and Brassica vegetables against fungal pathogens using seed treatment with beneficial bacteria with the focus on Verticillium longisporum causing Verticillium wilt in a wide range of plants.

Serratia plymuthica and Paenibacillus polymyxa were previously identified as promising biocontrol agents against Verticillium wilt in oilseed rape (Rybakova et al. 2015).

In order to understand the response of our biocontrol agents under different conditions, we compared the bio-priming, encapsulation and coating formulation protocols for Serratia plymuthica and Paenibacillus polymyxa. We found that the results were cultivar and disease-pressure dependent. While Serratia plymuthica showed mild reduction of disease symptoms in greenhouse and field trials, Paenibacillus polymyxa had in some cases negative impact on the seedlings. Therefore we screened endophytes of Brassicaceae for novel Verticillium longisporum antagonists that will replace Paenibacillus polymyxa and enhance the effect of the Serratia plymuthica strain by being the co-formulates for the optimized seed treatment against fungal diseases.

Field trials

From over 550 Brassica endophytic strains we selected five that showed antagonistic effects against Verticillium longisporum and were neither human- nor plant pathogens. The winter oilseed rape and cauliflower field trials using the combinations of the selected biocontrol agents were conducted by AGPL (Sweden). We studied biocontrol activity of the bacterial treatments in two field locations and compared their effects on two different cultivars of oilseed rape. The treatments with the biocontrol agent Serratia plymuthica resulted in mild reduction of Verticillium wilt symptoms in oilseed rape under some conditions. Interestingly, we found that the effects of the biocontrol treatments were cultivar specific and linked this specificity to the differences in the seed microbiomes of the studied cultivars.

Read more about our research in the following scientific publication

Rybakova D, Schmuck M, Wetzlinger U, Varo Suarez A, Murgu O, Müller H, Berg G (2015) Kill or cure? The interaction between endophytic Paenibacillus and Serratia strains and the host plant is shaped by plant growth conditions. Plant and soil:1-15

See our earlier updates on the Verticillium wilt research:

Read more about our activities on Verticillium wilt

Author

Gabriele Berg
Gabriele Berg
Soil-borne Verticillium wilt diseases in oil seed rape and vegetables
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