Shahabi, M. (2020) Genotypic and phenotypic identification of Azospirillum species of wheat and corn fields and evaluation of effects of dominant species on wheat and corn yield and Fusarium graminearum cotrol in Isfahan province. Doctoral thesis, University of Zabol.
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Genotypic and phenotypic identification of Azospirillum species of wheat and corn fields and evaluation of effects of dominant species.pdf Download (63kB) | Preview |
Abstract
Azospirillum bacteria are one of the most plant growth promoting rhizobacteria. They exist in the rhizosphere of many crop plants. In the research, some soil and plant roots were collected from wheat and maize rhizosphere of the plant fields in Isfahan. The samples were cultured in the tubes containing Nitrogen Free Bromothymol (NFB) semisolid media. To isolate Azospirillum strains, after the bacterial growth, the bacterial pellicles were streaked on NFB and Rojo Congo (RC) specific and semi-specific media to the bacterium. The bacteria were isolated based on morphological characteristics on the media and then were purified. Detection and identification of Azospirillum isolates was done using molecular tests by Az16S-A and Azo494-F/Azo756-R specific primers, 16S rRNA gene sequencing and standard bacteriology phenotypic tests. In PCR reaction, 646 and 263 bp fragments were amplified by Az16S-A and Azo494-F/Azo756-R primers, respectively, that confirmed the presence of Azospirilum bacteria. The results of the phenotypic tests based on Unweighted Pair-Group method using Arithmetic Average (UPGMA) and Jaccard's similarity coefficient (J) using NTSYS software, 2.01, classified Azospirillum isolates with 51% similarity in two main groups I and II. The sequencing of the 16S rRNA gene in some isolates determined at least three species of A. brasilense, A. lipoferum and A. zeae in rhizosphere of wheat and maize plants. The Azospirillum plant growth promoting characteristics (PGP) were determined by investigating the presence of NifH and NifD genes of nitrogenase. Examination of the properties of phosphate solubilization and production of chitinase, HCN, siderophores and indole acetic acid were also performed using specific tests. The amplification of 360 and 390 bp fragments by FdB260/FdB261 primers, respectively, confirmed the presence of NifH and NifD genes. Specific tests also revealed the ability of indole acetic acid production, insoluble phosphate solubilization with average value of 15 and 18.8 mg/l, respectively, and siderophore production in the isolates, and showed that some of the isolates possessed several PGP properties, while some of the isolates had one or no characteristic. To investigate the effect of Azospirillum isolates on the performance of wheat and maize plants, seeds of the Back Cross Roshan and Pishgam varieties of wheat, and Single Cross 704 and SC1263 varieties of maize were disinfected and treated with the bacterial isolates. The seeds were planted and after 35 days, some growth characteristics of plants were measured. Azospirillum Az16 was determined as the most effective growth promoting isolate. In addition, the effect of plant growth promoting Azospirillum isolates on Fusarium graminearum was also studied after inoculation of pots with pathogenic fungi. The disease severity was 63% lower in the pots treated with Azospirillum Az16 compared to the control plants. The genomic profilings of different Azospirillum isolates produced unique band patterns and showed high genetic diversity between the isolates. According to the study, the Azospirillum isolates of wheat and maize fields of Isfahan province have different species and genetic diversity. The band patterns amplified using rep-PCR can be somewhat useful for classification of Azospirillum species.
| Item Type: | Thesis (Doctoral) |
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| Uncontrolled Keywords: | Azospirillum, Plant growth promoting, sequencing, rep-PCR, Genetic diversity |
| Subjects: | Q Science > QK Botany |
| Depositing User: | Mrs najmeh khajeh |
| Date Deposited: | 19 Oct 2021 09:59 |
| Last Modified: | 19 Oct 2021 09:59 |
| URI: | http://eprints.uoz.ac.ir/id/eprint/2815 |
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