GENETIC IMPROVEMENT OF SOME NITROGEN FIXING BACTERIA THAT PRODUCE PLANT GROWTH PROMOTORS

KHALED ABDEL-FATTAH HAMED;

Abstract


The present study was carried out in Department of Genetics,
Agriculture Center for Genetic Engineering and Biotechnology
(ACGEB), Faculty of Agriculture.
Plant growth promoting rhizobacteria are various soil
bacteria that are capable of producing beneficial effects in culture or
in a protected environment. They have potential in agriculture use
and can lead to increased yields of a wide variety of crops.
Azospirillum is one of the most studied PGPR. It reached
commercialization in several countries, including Argentina, Mexico, India,
Italy, and France. Azospirillum spp. are known for their ability to
produce plant hormones, as well as polyamines and amino acids in
culture media. Among these hormones, indoles, mainly indole-3-
acetic acid, cytokinins and gibberellins . These phytohormones alter
metabolism and morphology of plants, leading to better absorption of
minerals and water, consequently larger and healthier plants.
In the present study, isolation of Azospirillum spp. (30
isolates) was carried out. Isolates were evaluated for their capability
to produce IAA and cytokinin (primary and secondary screening).
They were identified depending on biochemical consideration
(Bergey's manual and BIOLOG) and molecular genetics (16SrDNA
gene). The most powerful isolate was subjected to genetic
improvement based on chemical and physical induction of mutation.
The chemical mutagens used were sodium azide, nitrosoguanidine
and acridine orange. The physical mutagen used was U.V. light.
Mutants were screened for Indoles and cytokinins depending on
specific bioassays. The best mutagen in the production of IAA and
cytokinin was U.V. light (4.020 μg/ml and 1.81 μg/ml) respectively.
Greenhouse experiment were carried out for two seasons on maize
plants to investigate the effect of the mutant strains of Azospirillum
brasilense on the vegetative parameters of the plant. The fermented
broth of the mutants was added to the MS and used in the
micropropagation of Paulownia spp. Ex-plants to investigate the
65
SUMMARY
Khaled A. Metwally, (2016), M.Sc., Fac. Agric., Ain Shams Univ.
effect of the phytohormones especially IAA and cytokinins on the
root length of the ex-plant.


Other data

Title GENETIC IMPROVEMENT OF SOME NITROGEN FIXING BACTERIA THAT PRODUCE PLANT GROWTH PROMOTORS
Other Titles التحسین الوراثي لبعض أنواع البكتریا المثبتة للنیتروجین والمنتجة للھرمونات النباتیة
Authors KHALED ABDEL-FATTAH HAMED
Issue Date 2016

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