Articles
LONG TIME PROGENY ANALYSIS OF TRANSGENIC VICIA NARBONENSIS LINES REGARDING THE COEXPRESSION OF TWO FOREIGN GENES LOCATED ON A SINGLE T-DNA
Article number
447_60
Pages
301 – 312
Language
Abstract
A transformation / regeneration system was developed for the grain legume Vicia narbonensis. A number of fertile plants were obtained after cocultivation of hypocotyl explants together with Agrobacterium tumefaciens strain C58C1pGV3850hygro.
The T-DNA of this construct confers hygromycin resistance and nopalin production.
The progeny of three such clones – harbouring a single copy of the T-DNA only – was analyzed.
In the first generation both characters were inherited according to Mendelian law.
Throughout self pollinations homozygous as well as hemizygous sublines were obtained and further characterized.
In order to follow the transmission of the two foreign genes for the hygromycin phosphotransferase (hph) and the nopaline synthase (nos) for a long period, biochemical and molecular analyses were performed up to the seventh generation.
The genetic stability as well as the stable expression of both characters was demonstrated for the majority of the homozygous sublines and their progenies.
For a small number of hemizygous but also for a few homozygous sublines some unexpected results were obtained regarding the coexpression of both characters.
This indicates that in some cases genetic instability and modification of parts of the integrated foreign DNA – especially the hph gene – took place.
In a few hemizygous plants various DNA modification patterns of the hph gene seem to occur, leading to a multicellular mosaic in respect to the methylation status of parts of the T-DNA. Two homozygous sublines originating from two different transgenic clones were found to be instable.
Detailed analysis of this two subprogenies showed both partial or complete loss of the character “hygromycin resistance” as well as a “restoration” of the original phenotype too.
The T-DNA of this construct confers hygromycin resistance and nopalin production.
The progeny of three such clones – harbouring a single copy of the T-DNA only – was analyzed.
In the first generation both characters were inherited according to Mendelian law.
Throughout self pollinations homozygous as well as hemizygous sublines were obtained and further characterized.
In order to follow the transmission of the two foreign genes for the hygromycin phosphotransferase (hph) and the nopaline synthase (nos) for a long period, biochemical and molecular analyses were performed up to the seventh generation.
The genetic stability as well as the stable expression of both characters was demonstrated for the majority of the homozygous sublines and their progenies.
For a small number of hemizygous but also for a few homozygous sublines some unexpected results were obtained regarding the coexpression of both characters.
This indicates that in some cases genetic instability and modification of parts of the integrated foreign DNA – especially the hph gene – took place.
In a few hemizygous plants various DNA modification patterns of the hph gene seem to occur, leading to a multicellular mosaic in respect to the methylation status of parts of the T-DNA. Two homozygous sublines originating from two different transgenic clones were found to be instable.
Detailed analysis of this two subprogenies showed both partial or complete loss of the character “hygromycin resistance” as well as a “restoration” of the original phenotype too.
Authors
S. Brinkmann, T. Pickardt, S. Mahmoodzadeh, O. Schieder, M. Meixner
Keywords
Vicia narbonensis, transgenic plants, gene expression, gene stability
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