ISOLATION AND CHARACTERIZATION OF INDOLE ACETIC ACID PRODUCING PLANT GROWTH PROMOTING RHIZOBACTERIA FROM RHIZOSPHERIC SOIL OF WITHANIA SOMNIFERA

Abstract

Indole acetic acid (IAA) production is a major property of rhizosphere bacteria that plays a central role in plant growth and development as a regulator of cell division , cell differentiation , cell expansion, lateral root formation, flowering, and tropic responses. The present study deals with isolation, functional characterization and iden tification of IAA producing rhizo bacteria from the rhizosphere. The present study deals with the emerging need to protect medicinal plants that r epresent our natural resources. A total ten bacterial isolates were recovered from rhizospheric soil associated with Withania somnifera , recognized as bacillus spp. by morphotpic and biochemical characterization and tested for indole acetic acid production . Out of ten rhizobacterial isolates, six were selected as efficient Producers of IAA. The amount of indole acetic acid produ ced was detected in the presence of different concentration of tryptophan, which lead to the elevation in indole acetic acid produc tion as compared in the absence of tryptophan. The IAA production was further confirmed by thin layer chromatography (TLC). The impact of PGPR was evaluated on Withania somnifera seeds that showed significant elevation in germination %, root and shoot leng th as compared to the untreated seeds. Out of the chosen PGPR, WSNb3, WSNb5 and WSNb6 were showed to be the best to produce IAA . Subsequently, effect on plant growth was tested by towel paper assay. In conclusion the study suggests the IAA producing bacter ia may be efficient biofertilizer inoculants to promote plant growth and protecting the medicinal plants for the future generation.