2008 A P P L I E D A N D N A T U R A L S C I E N C E F O U N D A T I O N   Journal of Applied and Natural Science 6 (2): 473-479 (2014) Burkholderia sp. from rhizosphere of Rhododendron arboretum: Isolation, identification and plant growth promotory (PGP) activities Shweta Nailwal, Md. Shahbaz Anwar* , Kamal Kant Budhani, Amit Verma 1 , Tapan Kumar Nailwal Department of Biotechnology, Kumaun University Nainital, Bhimtal Campus, Bhimtal-263136 (Uttarakhand), INDIA 1 Department of Biochemistry, GBPUA and T, Pantnagar- 263145 (Uttarakhand), INDIA *Corresponding author. E-mail: shahbazmicro@gmail.com Received: May 18, 2014; Revised received: August 22, 2014 ; Accepted: October 10, 2014 Abstract: Plant growth promoting rhizobacteria (PGPR) is beneficial bacteria that colonize plant roots and enhance plant growth by wide variety of mechanism like phosphate solubilisation, etc. Use of PGPR has steadily increased in agriculture and offers an attractive way to replace chemical fertilizers, pesticides and supplements. The present research work was designed to isolate and characterize the PGP activity of Burkholderia sp. For this purpose rhizospheric soil from Rhododendron arboreum of Kumaun Himalaya was collected and efficient bacterial strain was screened on the basis of phosphate solubilization. Further, assessment of various parameters of plant growth promotion activity was done and enhanced production of IAA (16.4 μgml -1 ) and (20.8 μgml -1 ) was observed in the presence of 250μgml -1 and 500 μg ml -1 of tryptophan, respectively. Correspondingly, in respect of 7.8 μg ml -1 IAA without tryptophan, and their confirmation was executed by TLC. A remarkable change in color from green to reddish-brown zone on CAS plates, suggests the positive result for siderophore production, and finally the seed germination and pot trial experiment depicted the growth index of wheat plant. Therefore, the present study suggests that Burkholderia sp. is beneficial for plant growth promotion. Keyword: Burkholderia sp., IAA, PGPR, Phosphate solubilization, Siderophore INTRODUCTION Plant growth promoting rhizobacteria (PGPR) are group of bacteria that actively colonize plant roots and increase plant growth and yield. The mechanism by which PGPR promote plant growth is not fully understood, but it is thought to include the ability to produce phytohormones, asymbiotic N fixation against phytopathogenic microorganisms by production of siderophores, synthesis of antibiotics, enzymes and fungicidal compounds (Ahmad et al., 2006). In this connection the beneficial, root-colonizing, PGPR are defined by three intrinsic characteristics: (i) they must be able to colonize the root, (ii) they must survive and multiply in microhabitats associated with the root surface, in competition with other micro biota, at least for the time needed to express their plant promotion/protection activities, and (iii) they must promote plant growth. Several novel techniques to identify and characterize the PGPR and to study the colonization pattern and molecular determinants of root colonization have been extensively discussed (Gamalero et al., 2004). PGPR can affect plant growth by different direct and indirect mechanisms (Naz et al., 2012) like enhanced resistance to pathogenic diseases (Shobha and Kumudini, 2012). Direct methods of ISSN : 0974-9411 (Print), 2231-5209 (Online) All Rights Reserved © Applied and Natural Science Foundation www.ansfoundation.org increasing plant growth are through production of phytohormones, such as auxin, cytokinin and gibberellin. Screening PGPR isolates for quantity of auxin production has been proposed as a mechanism for selecting PGPR species for wheat inoculation (Khalid et al., 2004). These studies indicate that higher the plant growth promoting activities of rhizobacteria, higher is the chance of increased plant growth under different conditions. Hence, isolation and characterization of strains with higher plant growth promoting abilities, adapted under certain climates, can be very useful for the production of effective biofertilizers (Dastager et al., 2010; Abbas et al., 2010). A number of different bacteria promote plant growth, including Azotobacter sp., Azospirillum sp., Pseudomonas sp., Bacillus sp. and Acetobacter sp. (Turan et al., 2006). Plant growth promoting bacteria are important in managing plant growth because of their effects on soil conditions, nutrient availability, growth and yields. Therefore, the aim of this study was to check various PGPR activities of isolated and screened, phosphate solubilizing bacteria. For this purpose the PGP rhizobacteria was isolated as well as screened out and in conclusion characterized on the base of their direct (IAA production) and indirect (Siderophore production) plant growth promoting activities along with the measurement of their growth