title: Biocontrol Potential ofStreptomyces hydrogenansStrain DH16 towardAlternaria brassicicolato Control Damping Off and Black Leaf Spot ofRaphanus sativus.
abstract: Biocontrol agents and their bioactive metabolites provide one of the best alternatives to decrease the use of chemical pesticides. In light of this, the present investigation reports the biocontrol potential ofStreptomyces hydrogenansDH16 and its metabolites towardsAlternaria brassicicola, causal agent of black leaf spot and damping off of seedlings of crucifers.In vitroantibiosis of strain against pathogen revealed complete suppression of mycelial growth of pathogen, grown in potato dextrose broth supplemented with culture supernatant (20% v/v) ofS. hydrogenansDH16. Microscopic examination of the fungal growth showed severe morphological abnormalities in the mycelium caused by antifungal metabolites.In vivostudies showed the efficacy of streptomycete cells and culture supernatant as seed dressings to control damping off ofRaphanus sativusseedlings. Treatment of pathogen infested seeds with culture supernatant (10%) and streptomycete cells significantly improved seed germination (75-80%) and vigor index (1167-1538). Furthermore, potential of cells and culture supernatant as foliar treatment to control black leaf spot was also evaluated. Clearly visible symptoms of disease were observed in the control plants with 66.81% disease incidence and retarded growth of root system. However, disease incidence reduced to 6.78 and 1.47% in plants treated with antagonist and its metabolites, respectively. Additionally, treatment of seeds and plants with streptomycete stimulated various growth traits of plants over uninoculated control plants in the absence of pathogen challenge. These results indicate thatS. hydrogenansand its culture metabolites can be developed as biofungicides as seed dressings to control seed borne pathogens, and as sprays to control black leaf spot of crucifers.
authors.affiliation: Department of Microbiology, Guru Nanak Dev University Amritsar, India.
authors.forename: Rajesh K
authors.initials: RK
authors.lastname: Manhas
authors.affiliation: Department of Microbiology, Guru Nanak Dev University Amritsar, India.
authors.forename: Talwinder
authors.initials: T
authors.lastname: Kaur
keywords: Alternaria brassicicola; Raphanus sativus; Streptomyces hydrogenans DH16; biocontrol; culture supernatant