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Root specific expression of the GUS reporter gene was observed when transformed plants were grown fully inside solid media both under P and +P and on MS media containing kanamycin. However, there was no GUS activity when plants were grown on the surface of the solid media and hydroponically under P and +P conditions. Morphological root assessment for the knockout plants has shown no difference between the knockout genotypes and the wild type. Thus, contrary to previous result, in this study other stress than phosphorus deficiency factors were assumed to be contributing for the expression of the GUS reporter gene in all the constructs. Oxygen stress, mechanical impedance and stress due to the selective marker during seedling growth were thought to be possible reasons. However, since the effect of growing conditions was not evaluated before, this investigation needs further verification. Additionally, quantifying the GUS reporter gene activity in the transformant plants grown under - P and +P conditions by real time PCR helps to explore the real function of these genes.

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Kefyalew Negisho Bayissa,MSc. in International Horticulture Leibniz University of Hanover, Germany.Research thesis " Analysis of Genes Differentially Expressed Under Phosphorus Deficiency in Roots of Brassica carinata by Promoter GUS in Arabidopsis thaliana. Researcher at Holetta National Agricultural Biotechnology Research Program, Ethiopia

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