SHIRKOT, C.K.GAUTAM, SWATI2017-05-122017-05-122014http://krishikosh.egranth.ac.in/handle/1/5810011061ABSTRACT Bacterial canker caused by Clavibacter michiganensis subsp. michiganensis is known to cause significant economic losses to tomato production worldwide. Biological control has been proposed as an alternative to current chemical containment methods, which are often inefficient and may leave adverse effects on the environment. However, only little headway has so far been made in developing biocontrol strategies against C. michiganensis subsp. michiganensis. To address this knowledge gap, we investigated the antagonistic capacity of different PGPRs having multifarious plant growth promoting traits (P-solubilization, IAA production, siderophore production, lytic enzyme activity, and ability to fix atmospheric nitrogen) on C. michiganensis under in vitro and in planta conditions. PGPRs are highly diverse and in this study we focus on rhizobacteria as biocontrol agents. Their effects can occur via local antagonism to soil-borne pathogens or by induction of systemic resistance against pathogens throughout the entire plant. Several substances produced by antagonistic rhizobacteria have been related to pathogen controland indirect promotion of growth in many plants, such as siderophores, lytic enzymes and antibiotics. Induced systemic resistance (ISR) in plants resembles pathogen-induced systemic acquired resistance (SAR) under conditions where the inducing bacteria and the challenging pathogen remain spatially separated. Five antagonistic bacterial isolates were tested for biocontrol potential against C. michiganensis under net house conditions. Isolate S1 showed maximum reduction in disease incidence and disease index along with maximum increase in plant growth parameters. The isolate was identified as Bacillus amyloliquefaciensby 16S rDNA sequencing. Therefore, strain S1 had considerable biocontrol potential as well as plant growth promoting ability and could be used as a potential biocontrol agent against bacterial canker of tomato.ennullThesis