Antagonism of Pseudomonas putida Against Dematophora nectarix A Major Apple Plant Pathogen and Its Potential Use as a Biostimulent

Plant growth promoting rhizobacteria prove a key to sustainable agriculture provided they effectively colonize roots, survive, proliferate in the rhizosphere and enhance plant growth by a variety of mechanisms. In the present study, several samplings were conducted in different apple growing regions of Himachal Pradesh in order to isolate a strain capable of showing multifarious plant growth promoting activities and antagonism against Dematophora nectarix a major apple plant pathogen. In this research five isolates of fluorescent Pseudomonas sp. were isolated from apple rhizosphere. Out of five isolates, one isolate DE-18 was selected on the bases of high production of PGP activities and was identified by 16S rRNA gene sequencing. The isolate DE-18 showed maximum phosphate solubilisation and siderophore production of 425 [micro]g/ml and 42.18 %SU respectively. Among the five isolate, DE-18 showed production of both protease (40 mm) and chitinase (28 mm). The isolate DE-18 also showed antagonism against Dematophora nectarix (38.46%) and Phytopathora cactoram (36.18%) and can act as Bioprotectant. The 16S rDNA based phylogenetic analysis demonstrated that the isolate DE-18 belonged to the Pseudomonas putida and sequence was deposited in the GenBank nucleotide sequence databases under accession number KU139388. Keywords: PGPR, Pseudomonas putida, Dematophora nectarix, Biocontrol efficacy.