Genetic diversity of rhizobia nodulating sesbania cultivars in Indian soils
| dc.contributor.advisor | Gera, Rajesh | |
| dc.contributor.author | Kuldeep | |
| dc.date.accessioned | 2018-10-26T05:52:00Z | |
| dc.date.available | 2018-10-26T05:52:00Z | |
| dc.date.issued | 2018 | |
| dc.description.abstract | The genus Sesbania contains about 70 species widespread over tropical and subtropical regions. The genus has attracted interest for its fast growth, high crop yield, flood tolerance, root as well as stem nodulation with high nitrogen (N2) fixation activity. Due to their importance and diversity within natural populations, identification and characterization of rhizobial strains imply a comprehensive and accurate approach. Yet little is known of the rhizobia that associate with different Sesbania species in terms of their distribution, diversity, ecology or taxonomic status. Therefore, the present investigation was undertaken for genetic diversity of rhizobia nodulating Sesbania cultivars in Indian soils. A total of 70 rhizobial isolates of different Sesbania species were isolated from 56 soil samples collected from different locations of India using trap plant method. These mainly include 14 isolates of S. sesban, 20 of S. grandiflora, 10 of S. aculeata, 10 of Sesbania rostrata (root nodulating) and 16 of S. rostrata (stem nodulating). The authenticity of these rhizobial isolates were tested on the basis of Gram‟s staining, Hofer‟s alkaline medium, Ketolactase and acid or alkaline production tests. All rhizobia were able to produce IAA and ammonia, however, 79, 40 and 27% rhizobia had the ability of phosphate solubilization, siderophore production and bacteriocin production, respectively, whereas, 54% of rhizobia were able to utilize ACC. On the basis of different PGP traits and nodulation efficiency under aseptic controlled conditions, 20 promising rhizobial isolates were selected. Most of these isolates were found to have intrinsic antibiotic resistance to ampicillin, chloramphenicol, nalidixic acid and streptomycin upto concentration of 100 μg ml-1. The Genomic DNA of selected rhizobial isolates for different Sesbania species was amplified for 16S rRNA gene using BAC27F and BAC1378R primers using standard PCR amplification conditions. ARDRA results showed enormous diversity among themselves and divergence among different Sesbania rhizobial isolates was initiated at approximately 54-65% levels of similarity coefficient. These isolates were distributed into two major groups and further into various sub and sub-sub groups. Sole carbon source utilization pattern (SCSUP) with 22 different sugars of 20 selected rhizobial isolates showed diverse sugar utilization pattern. Most of the isolates (88%) utilized dextrose as carbon source, while inulin was the least utilized source of carbon. Five rhizobial isolates; SSKr(ii), SGKe(i), SAMa, SRKr(i)/r and SRTn/s were found to have more nodule number and nodule fresh weight as compared to control and remaining isolates both under sterilized as well as unsterilized conditions. These rhizobial isolates also showed significant increase in shoot and root dry weight along with shoot N and P uptake in their respective crop tested. These isolates have tremendous potential in near future to be used as biofertilizers in salt affected, alkaline and waterlogged field conditions, which will not only improve nitrogen availability and plant growth in Sesbania spp. but also act as nitrogen reserve for next crop. The promiscuous Sesbania rhizobial isolates were identified as Rhizobium sp. on the basis of ribo-typing of partial 16S rRNA gene. | en_US |
| dc.identifier.uri | http://krishikosh.egranth.ac.in/handle/1/5810082192 | |
| dc.keywords | Sesbania, Rhizobia, Nodulation, Bacteriocin, Diversity | en_US |
| dc.language.iso | en | en_US |
| dc.publisher | CCSHAU | en_US |
| dc.sub | Microbiology | en_US |
| dc.subject | null | en_US |
| dc.theme | Genetic diversity of rhizobia nodulating sesbania cultivars in Indian soils | en_US |
| dc.these.type | Ph.D | en_US |
| dc.title | Genetic diversity of rhizobia nodulating sesbania cultivars in Indian soils | en_US |
| dc.type | Thesis | en_US |