Isolation and Characterization of Plant Growth Promoting Antagonistic Bacteria from Cotton and Sugarcane Plants for Suppression of Phytopathogenic Fusarium Species

BACKGROUND: Plant Growth Promoting Rhizobacteria (PGPR) may be utilized to augment plant growth and suppress the plant pathogens. Objective: The present study was conducted to isolate and characterize the antagonistic bacteria indigenous to cotton and sugarcane rhizosphere in Pakistan, and to evaluate their ability to suppress phytopathogenic Fusarium spp. Out of 63 isolates 37 different morphotypes were studied for their antagonistic activity against Fusarium monoliformae, Fusarium oxysporum and Fusarium solani. Among these 31 strains showed the percentage suppression ranging from 40 to 66% against Fusarium spp. OBJECTIVES: The antagonistic bacteria having antifungal activity were studied for different morphological and physiological characteristics using Gram staining and light microscopy. Most of them were Gram negative and tentatively identified as Pseudomonas spp. The selected strains were screened in vitro for plant growth regulation and antifungal traits. MATERIAL AND METHODS: Our study included 1000 premature CAD patients that classified into two groups with history of MI (n = 461) and without of MI (n = 539). The polymorphism variants in 10% of samples were determined by PCR-RFLP technique and genotyping of the polymorphism in all subjects was conducted by High Resolution Melting method. Given the two conditions of patients residing in Tehran and also faced with their first episode of MI, 640 out of 1000 study samples that had been previously followed-up were assessed in a retrospective cohort phase regarding long-term major adverse cardiac events (MACE). RESULTS: Four bacterial strains were able to produce the chitinase enzyme while four other bacterial strains showed protease production. Ten strains were positive for HCN production. Out of 37, eight strains showed phosphate solubilization ranging from 13 to 24 µg/ml. eighteen strains produced indole acetic acid ranging from 5 to 19 µg/ml. CONCLUSIONS: This study identified specific traits in the isolated rhizobacteria which make them good candidates as PGPR and might contribute to enhance growth of crop plants. This information is of general interest and also helpful for devising strategies to manage diseases caused by Fusarium in cotton and sugarcane.