International Journal of Current Microbiology and Applied Sciences

ISSN: 2319-7706 Volume 2 Number 6 (2013) pp. 127-136

Studies on phytohormone producing ability of indigenous endophytic bacteria isolated from tropical legume crops

T. UmaMaheswari1 , K. Anbukkarasi1 , T. Hemalatha2* and K. Chendrayan1

1Department of Agricultural Microbiology, Tamil Nadu Agricultural University, Coimbatore-641 003, India 1Department of Bioproducts, Central Leather Research Institute, Adyar, Chennai-600020, India *Corresponding author e-mail: hemabiotek.t@gmail.com

A B S T R A C T

Bacterial endophytes are known to reside inside tissues of plants and can form a range of different relationships including symbiotic, mutualistic, commensalistic and trophobiotic. There has been increasing evidence, that endophytic bacteria can influence plant growth significantly by the production of phytohormones analogous to plant growth promoting rhizobacteria (PGPR) activity. In the present study, endophytic bacteria were isolated from various tropical grain legume crops namely redgram, blackgram, greengram, cowpea and chickpea. The population of endophytes in the roots, stems and leaves of different legume plants ranged from 2.1 103 to 8.6 103 , 1.5 103 to 5.0 103 and 0.3 to 2.3 103 respectively. Based on the polyphasic characterization, 25 distinct isolates obtained were identified as Bacillus sp, Micrococcus sp, Pseudomonas sp, Flavobacterium sp and Serratia sp. All the isolates were evaluated for the production of phytohormones viz. gibberellic acid (GA), indole acetic acid (IAA) and cytokinin. The endophytic isolates produced GA from 0.75 to 2.83 g ml-1 , had an IAA activity between 0.12 g ml-1 to 6.46 g ml-1 and cytokinin values were 0.52 g ml-1 to 2.96 g ml-1 . Hence the present study clearly establishes the beneficial effect of bacterial endophytes on tropical legumes.

Keywords

Endophytic bacteria; tropical grain; legume crops; phyto- hormones.