Bacterial phyllosphere communities of Solanum tuberosum L. and T4-lysozyme-producing transgenic variants

Abstract

Bacterial communities in the phyllosphere of genetically modified potato plants carrying a T4-lysozyme gene and of control plants without the gene were compared in the greenhouse and in the field. The polyphasic investigation included characterisation of isolates by fatty acid analysis, community-level catabolic profiling in BIOLOG GN microplates and genetic community fingerprinting by denaturing gradient gel electrophoresis of 16S rDNA fragments amplified by PCR from community DNA (PCR-DGGE). The diversity and frequency distribution of species determined by fatty acid analysis of 190 isolates from a greenhouse experiment and 488 isolates from a field sampling, as well as PCR-DGGE fingerprints of phyllosphere samples from the field, indicated highly similar communities of T4-lysozyme plants and controls. In addition, effects on community-level catabolic profiles were detected neither in the greenhouse nor in the field trial. Differences in the percentages of culturable species were detectable for the T4-lysozyme plants, namely a higher percentage of isolates classified as Erwinia sp. and lower abundances of Gram-positive isolates and of Agrobacterium, but the observed effects were minor relative to the natural variability observed in several field samplings. The observed effect on Agrobacterium populations in the field was confirmed by PCR-DGGE.