Plant growth-promoting and antagonistic endophytic bacteria from the medicinal plant Tinospora cordifolia stem

Abstract

Endophytic bacteria residing within the plant tissues are poorly investigated microorganisms. A total of 35 endo- phytic bacteria isolated from Tinospora cordifolia stem tissue samples collected from 3 different districts of Punjab, India were screened for phosphate solubilization, IAA-like auxin production, ACC-deaminase activity, and pro- duction of siderophores, hydrogen cyanide and ammonia. Out of these bacteria, 11 showing multiple plant growth-promoting activities were screened for anatagonism against phytopathogens Fusarium moniliforme, Alternaria alternata and Curvularia lunata. One isolate TCA2 showed broad-spectrum activity with 38% growth inhibition in Alternaria alternata, 35% inhibition in Fusarium moniliforme and 25% inhibition in Curvularia lunata. On the basis of 16S rDNA gene sequencing, the isolate TCA2 has been identified as Pseudomonas sp. The maize plants inoculated with the bacterial isolate TCA2 showed 33.1%, 31.6%, and 38.4% increased root length, shoot length and dry weight, respectively, over the respective inoculated controls in pots under natural conditions. In the pre- sent studies, Pseudomonas sp. TCA2 with multiple plant growth-promoting activities has been selected as a sui ta- ble candidate for the development of microbial inoculants.