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

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 ofPseudomonas aeruginosaZ5 isolated from cotton grown in Pakistani soils for the suppression ofFusarium oxysporumassociated with cotton seedling disease. In dual culturing techniques, four bacterial strains inhibited fungal pathogens, i.e.F. oxysporum,Fusarium moniliforme,Fusarium solaniandRhizoctonia solani, significantly with percent inhibition ranging from 25% to 91.5%.P. aeruginosaZ5 showed maximum suppression of all the tested pathogens. Net-house experiments showed that the application ofP. aeruginosaZ5 both separately and in combination withBacillus fusiformisS10 significantly reduced the disease incidence by suppressingF. 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 withP. aeruginosaZ5 showed its good colonisation aptitudes even in the presence of high inoculation of soil withF. oxysporum. Confocal laser scanning microscopy supported the root colonisation of cotton plants with fluorescently labelledP. aeruginosaZ5. Because of innate fungicidal potential, growth promotingP. aeruginosaZ5 can be used as a bioinoculant and an antagonist to suppress the growth of cotton root-associated fungal pathogen. [ABSTRACT FROM AUTHOR]