Serratia marcescens G4 as a novel biocontrol strain against Sclerotinia sclerotiorum infection in soybean.

BACKGROUND

Sclerotinia is a soil-borne disease of soybean caused by Sclerotinia sclerotiorum, which seriously endangers the yield and quality of soybean. The purpose of this study was to explore effective biocontrol bacteria for controlling soybean Sclerotinia.

RESULTS

In this study, we isolated 32 strains of bacteria from soybean rhizosphere soil. The inhibition rate of strain G4 on Sclerotinia sclerotiorum was the highest (82.27%). Strain G4 was identified as Serratia marcescens by morphological, physiological, biochemical and 16S rDNA sequence analysis. The strain G4 could inhibit the growth of Sclerotinia sclerotiorum and change the mycelial morphology. Under the conditions of 5.0 × 10 CFU/mL, pH 7 and 30 °C, the antibacterial rate of strain G4 was the highest, which was 92.10%. After the treatment of strain G4, the content of reducing sugar and soluble protein of Sclerotinia sclerotiorum showed a downward trend, which inhibited its growth. In addition, strain G4 could reduce the activity of cell wall degrading enzymes of Sclerotinia sclerotiorum. In vitro and pot experiments showed that Serratia marcescens had an inhibitory effect on Sclerotinia sclerotiorum. After treatment with strain G4, the content of defense-related enzymes and malondialdehyde in plants increased. The results showed that Serratia marcescens G4 isolated from soybean rhizosphere soil was an effective biocontrol strain against soybean Sclerotinia.

CONCLUSION

Serratia marcescens G4 has a strong inhibitory effect on Sclerotinia sclerotiorum and can be used as a biocontrol bacterium to control the infection of soybean Sclerotinia. © 2025 Society of Chemical Industry.