Bio-organic fertilizers stimulate indigenous soil Pseudomonas populations to enhance plant disease suppression

Abstract

Background Plant diseases caused by fungal pathogen result in a substantial economic impact on the global food and fruit industry. Application of organic fertilizers supplemented with biocontrol microorganisms (i.e. bioorganic fertilizers) has been shown to improve resistance against plant pathogens at least in part due to impacts on the structure and function of the resident soil microbiome. However, it remains unclear whether such improvements are driven by the specific action of microbial inoculants, microbial populations naturally resident to the organic fertilizer or the physical-chemical properties of the compost substrate. The aim of this study was to seek the ecological mechanisms involved in the disease suppressive activity of bio-organic fertilizers. Results To disentangle the mechanism of bio-organic fertilizer action, we conducted an experiment tracking Fusarium wilt disease of banana and changes in soil microbial communities over three growth seasons in response to the following four treatments: bio-organic fertilizer (containing Bacillus amyloliquefaciens W19), organic fertilizer, sterilized organic fertilizer and sterilized organic fertilizer supplemented with B. amyloliquefaciens W19. We found that sterilized bioorganic fertilizer to which Bacillus was re-inoculated provided a similar degree of disease suppression as the non-sterilized bioorganic fertilizer across cropping seasons. We further observed that disease suppression in these treatments is linked to impacts on the resident soil microbial communities, specifically by leading to increases in specific Pseudomonas spp.. Observed correlations between Bacillus amendment and indigenous Pseudomonas spp. that might underlie pathogen suppression were further studied in laboratory and pot experiments. These studies revealed that specific bacterial taxa synergistically increase biofilm formation and likely acted as a plant-beneficial consortium against the pathogen. Conclusion Together we demonstrate that the action of bioorganic fertilizer is a product of the biocontrol inoculum within the organic amendment and its impact on the resident soil microbiome. This knowledge should help in the design of more efficient biofertilizers designed to promote soil function.

Response of Soil Bacterial Community to Application of Organic and Inorganic Phosphate Based Fertilizers under Vicia faba L. Cultivation at Two Different Phenological Stages

“…Considering that, varying C compound and nutrient components tend to influence the microbial community [67,68], further fluctuations in community compositions are due to the contrasting chemical composition of the used fertilizers amendments. Recent findings by Tao et al [69] support increase of Pseudomonas in VTLW treatment, as authors reported that bioorganic fertilizers tend to increase indigenous Pseudomonas. Cyanobacteria abundance tends to increase in the optimal combination of biogenic elements in soil, such as reduced nitrogen content under a sufficient amount of phosphorus [60], which could underpin the higher abundance of these bacteria in PT treatment, which contain higher phosphorus.…”

Plant Growth-Promoting Rhizobacteria HN6 Induced the Change and Reorganization of Fusarium Microflora in the Rhizosphere of Banana Seedlings to Construct a Healthy Banana Microflora

“…Although decades of research have been carried out on banana Fusarium wilt, there are few effective control methods for this disease, and the breeding of disease-resistant varieties is the most effective management strategy ( Tao et al, 2020 ). However, these kinds of biological resources are usually scarce, unproductive, and commercially unacceptable ( Dita et al, 2010 ).…”

Agronomic Efficiency of Animal-Derived Organic Fertilizers and Their Effects on Biology and Fertility of Soil: A Review

“…In a continuation, Bonanomi et al [21] demonstrated that organic amendments with high labile C fractions would be conducive to plant damping-off disease in short-term but, became suppressive after 100-300 days of application. Recently, Tao et al [204] showed that the addition of bio-organic fertilizer shielded plants from pathogen infection increasing synergistic formation of biofilm at the root-microbiome interface, which may act as a plant-beneficial consortium against the soil-borne phytopathogens. An overall depiction of animal waste recycling and their reuse in farming systems to intensify agricultural productivity is reflected in Figure 2.…”