Seed coating with the synthetic consortium of beneficial Bacillus microbes improves seedling growth and manages Fusarium wilt disease

Fusarium wilt disease of the pea crop caused by the infection of Fusarium oxysporum f. sp. pisi (FOP) is a serious soilborne disease. In this study, we developed a seed coating containing a synthetic consortium of beneficial Bacillus microbes to manage the fusarium wilt disease. Three bacterial strains IS1, IS6, and IS7 isolated from the rhizosphere of different healthy-looking crop plants, were selected for the seed coating based on antagonism against the FOP shown during in-vitro studies, and suppression of fusarium wilt disease when applied as seed priming in preliminary pot trials. The strains were identified as B. subtilis (IS1), B. amyloliquificiens (IS6), and B. fortis (IS7) by 16 s rRNA gene sequencing. The seed coating with the consortium of all three bacterial strains showed a significant positive effect on seed germination, seedling height, and biomass accumulation of pea seedlings. Upon exposure to FOP, a > 50 % reduction in disease index was seen in pea plants raised from coated seeds than the pathogen control along with the ameliorative effect on plant growth attributes. Besides, the coating of consortium induced significant up-regulation of total phenolic compounds and enzymes of phenyl-propanoid pathways. Additionally, the non-targeted metabolomic analysis indicated a large number of perturbations in amino acids, sugars, carbohydrates, and phenylpropanoids in pea plants raised from consortium-coated seeds and subsequently challenged with FOP. Based on the findings, consortium coating of Bacillus spp. on pea seeds may have the potential to develop a bio-based remedy for the management of wilt diseases in pea plants and improvement in growth attributes.

Automated summary

A seed coating containing a synthetic consortium of beneficial Bacillus microbes was developed to manage Fusarium wilt disease in pea crops. The coating showed positive effects on seed germination, seedling height, and biomass accumulation. Coated seeds exhibited reduced disease index and enhanced plant growth attributes when exposed to FOP. The seed coating also induced up-regulation of phenolic compounds and enzymes of the phenylpropanoid pathway. Metabolomic analysis revealed perturbations in amino acids, sugars, carbohydrates, and phenylpropanoids in plants raised from coated seeds and challenged with FOP.