Evaluation of Pseudomonas aeruginosa Z5 for biocontrol of cotton seedling disease caused by Fusarium oxysporum

Abstract

Plant growth-promoting bacteria-mediated biocontrol of plant pathogens is renowned to enhance the growth of the plants using different direct or indirect mechanisms. The goal of the present investigation was the evaluation of Pseudomonas aeruginosa Z5 isolated from cotton grown in Pakistani soils for the suppression of Fusarium oxysporum associated with cotton seedling disease. In dual culturing techniques, four bacterial strains inhibited fungal pathogens, i.e. F. oxysporum, Fusarium moniliforme, Fusarium solani and Rhizoctonia solani, significantly with percent inhibition ranging from 25% to 91.5%. P. aeruginosa Z5 showed maximum suppression of all the tested pathogens. Net-house experiments showed that the application of P. aeruginosa Z5 both separately and in combination with Bacillus fusiformis S10 significantly reduced the disease incidence by suppressing F. oxysporum (the causal agent of cotton seedling disease) up to 64–65% and improved the percent germination as compared to the infected control plants. The production of antibiotics, proteases and siderophores may be the contributing factors for its antagonistic properties. Highest bacterial population (8.9 CFU/g root) observed on roots of cotton plants inoculated with P. aeruginosa Z5 showed its good colonisation aptitudes even in the presence of high inoculation of soil with F. oxysporum. Confocal laser scanning microscopy supported the root colonisation of cotton plants with fluorescently labelled P. aeruginosa Z5. Because of innate fungicidal potential, growth promoting P. aeruginosa Z5 can be used as a bioinoculant and an antagonist to suppress the growth of cotton root-associated fungal pathogen.

Keywords:

• Pseudomonas aeruginosa
• biocontrol
• cotton seedling disease
• Fusarium oxysporum

Acknowledgement

We are thankful to Mr. Tariq Mehmood, Mr. Naveed and Mr. Tariq Shah (Technical Assistant, NIBGE) for their assistance.

Funding

This work was supported by IAEA TC Project No. PAK/5/037 and BIRCEN project funded by IDB.

Additional information

Funding

Funding: This work was supported by IAEA TC Project No. PAK/5/037 and BIRCEN project funded by IDB.