Methods and detection limits in tracking a genetically modifiedPseudomonas sp. released in the pine phyllosphere

Genetically modified entomopathogenic bacteria, recent developments, benefits and impacts: A review

Entomopathogenic bacteria (EPBs), insect pathogens that produce pest-specific toxins, are environmentally-friendly alternatives to chemical insecticides. However, the most important problem with EPBs application is their limited field stability. Moreover, environmental factors such as solar radiation, leaf temperature, and vapor pressure can affect the pathogenicity of these pathogens and their toxins. Scientists have conducted intensive research to overcome such problems. Genetic engineering has great potential for the development of new engineered entomopathogens with more resistance to adverse environmental factors. Genetically modified entomopathogenic bacteria (GM-EPBs) have many advantages over wild EPBs, such as higher pathogenicity, lower spraying requirements and longer-term persistence. Genetic manipulations have been mostly applied to members of the bacterial genera Bacillus, Lysinibacillus, Pseudomonas, Serratia, Photorhabdus and Xenorhabdus. Although many researchers have found that GM-EPBs can be used safely as plant protection bioproducts, limited attention has been paid to their potential ecological impacts. The main concerns about GM-EPBs and their products are their potential unintended effects on beneficial insects (predators, parasitoids, pollinators, etc.) and rhizospheric bacteria. This review address recent update on the significant role of GM-EPBs in biological control, examining them through different perspectives in an attempt to generate critical discussion and aid in the understanding of their potential ecological impacts.

Monitoring a genetically modified Pseudomonas sp. released on pine leaves reveals concerted successional patterns of the bacterial phyllospheric community

The fate of a biocontrol agent released on pine phyllosphere in a greenhouse-confined trial was followed over 102 days. The microorganism used, a Pseudomonas sp., isolated from Pinus nigra, carries the cry9a toxin gene from Bacillus thuringiensis. In order to detect the GMM, specific primers were used, and a previously defined protocol for DNA isolation from bacteria colonizing pine needles was applied. The method, based on vortexing in a suspension of glass beads followed by microcolumn extractions, allowed sensitive PCR monitoring of the target transgenes. The presence of the released organism was recorded throughout the trial and compared with its entomocidal performance towards larvae of the pine processionary caterpillar Thaumetopoea pityocampa. At the same time the dynamics of the released Pseudomonas within the whole epiphytic bacterial community, was followed by amplifying 16S rDNA pools and comparing ARDRA profiles at seven sampling points. The resulting dendrogram allowed to follow the time-dependent progressive blending of the Pseudomonas profile into those of the resident biota. PCR-dominance of the released bacterium in the community was extended until 21 days from release while its activity against insect larvae lasted for over 3 months. The prokaryotic epiphytic population, irrespective of any particular impact from the released strain, showed no resilience but a general successional trend, which, remarkably, appeared synchronous on all trees tested, including non-inoculated controls. This observation suggests interesting patterns of concerted environmental shifts by phyllospheric microorganisms.