Endophytes of Jatropha curcas promote growth of maize

Endophytic bacteria reside within plant host without causing any adverse symptoms. These bacteria improves plant's performance under normal and adverse conditions including nutrient limitation, climate change and infections. Recently renewable energy (biodiesel) crop Jatropha curcas L (J.curcas) has received enormous support for mass cultivation. In addition, intercropping of J. curcas with agriculturally important crops has been recommended to improve crop yield. This plant easily grows under harsh environment and limited nutrient availability. It is hypothesized that J.curcas is capable of sustaining under theese challenging environment with the help of its beneficial microorganisms. Experiments were carried out to characterize the culturable endophytic bacteria of J.curcas and evaluate their plant growth promoting effect on maize (Zea mays L.). Population of culturable endphytic bacteria varied from 0.8 × 103 to 1.2 × 103 colony forming units (cfu) g-1 fresh plant tissue. Fifteen isolates were sequenced and characterized based on their carbon source utilization and plant growth promoting activities. 16 S rRNA genes of these isolates were mainly homologous to Paenibacillus, Brevibacillus, Sphingomonas and Rhizobium. These isolates preferred to grow on methanol, ethanol, glucose, fructose, sucrose, and gelatine. A Principal component analysis highlighted that PC1 contributed 43.32% variation while PC2 rendered 14.01% variation. These strains exhibited catalase, nitrate reductase, ACC deaminase and phosphatase activities. All isolates were positive towards phosphates and IAA production. Phosphatase activity (mg of PO4 released d-1) varied from 0.107 to 0.298, while IAA production ranged from 0.51 to 13.56 µg 10-6 cells 2d-1. Inoculation of the endophytes to maize seeds increased shoot and root length of seedlings significantly (p < 0.01) than the non-inoculated. Study highlighted that endophytic bacteria of J.curcas possesses plant growth promoting attributes which can be explored as microbial inoculants for agricultural crops.