Impact of barley (Hordeum vulgare L.) transgenic line H228.2A on substrate and rhizosphere microorganisms and the possibility of horizontal gene transfer

Abstract

Numerous investigations have been carried out to determine the impact of genetically modified plants, such as potato, maize, alfalfa and tobacco, on soil microorganisms and the results are contradictory. We applied classical microbiology methods to study quantitative changes of bacterial and fungal abundance in substrate and rhizosphere from barley (Hordeum vulgare L.) transgenic line H228.2A containing Rpg1 and bar genes, and its parent nontransgenic variety 'Golden Promise'. In addition, molecular biology methods were used to determine, if horizontal gene transfer from barley transgenic line to soil bacteria has occurred under experimental conditions by screening bacterial genomes for the presence of Rpg1 gene sequences using polymerase chain reactions. Results did not show significant impact on substrate and rhizosphere microorganisms. In the second pot experiment the average number of filamentous fungi in the rhizosphere of parent line 'Golden Promise' was higher than in the rhizosphere of transgenic line, but the variation among samples was very high probably caused by the high variation of substrate moisture content. None of bacterial deoxyribonucleic acid (DNA) samples isolated from substrate of rhizosphere of barley transgenic line resulted in positive amplification of Rpg1 gene-specific primer product.