Abstract

The phenotypic and genotypic characterization of eight rhizobial isolates obtained fromArachis hypogaeanodules grown under stress environment was performed. Isolates were screened for their ability to tolerate different abiotic stresses (high temperature (60 degrees C), salinity (1-5% (w/v) NaCl), and pH (1-12). The genomic analysis of 16S rRNA and housekeeping genes (atpD,recA, andglnII) demonstrated that native groundnut rhizobia from these stress soils are representatives of fast growers and phylogenetically related toRhizobium sp. The phenotypic characterization (generation time, carbon source utilization) also revealed the isolates as fast-growing rhizobia. All the isolates can tolerate NaCl up to 3% and were able to grow between 20 and 37 degrees C with a pH between 5 to 10, indicating that the isolates were alkali and salt-tolerant. The tested isolates effectively utilize mono and disaccharides as carbon source. Out of eight, three rhizobial isolates (BN-20, BN-23, and BN-50) were able to nodulate their host plant, exhibiting their potential to be used as native groundnut rhizobial inoculum. The plant growth promoting characterization of all isolates revealed their effectiveness to solubilize inorganic phosphate (56-290 mu g mL(-1)), synthesize indole acetic acid (IAA) (24-71 mu g mL(-1)), and amplification of nitrogen fixingnifHgene, exploring their ability to be used as groundnut biofertilizer to enhance yield and N-2-fixation for the resource poor farmers of rainfed Pothwar region.

Keywords

Arachis hypogaea; abiotic stress; Rhizobium; 16S rRNA; housekeeping genes; phenotypic characterization; biofertilizer

Published in

Sustainability
2020, volume: 12, number: 15, article number: 6259
Publisher: MDPI

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