Molecular Investigations of the Soil, Rhizosphere and Transgenic Glufosinate-Resistant Rape and Maize Plants in Combination with Herbicide (Basta^®) Application under Field Conditions

Abstract

A field study was conducted during 1994 to 1998 on the Experimental Farm Roggenstein, near Fürstenfeldbruck, Bavaria, Germany to determine the effect of transgenic glufosinateresistant rape in combination with the herbicide Basta " [glufosinate-ammonium, phosphinothricin, ammonium (2RS)-2-amino-4-(methylphosphinato) butyric acid] application on soil microorganisms and the behaviour of the synthetic transgenic DNA in response to normal agricultural practice. No influence of Basta " on microbial biomass could be detected. The phospholipid fatty acid analysis of soil extracts showed no difference between Basta " application and mechanical weed control, whereas conventional herbicide application revealed a different pattern. Basta " application resulted in a changed population of weeds with a selective effect for Viola arvensis. During senescence, transgenic rape DNA was degraded similar to endogenous control DNA. After ploughing the chopped plant material in the soil, transgenic as well as endogenous control DNA sequences could be detected for up to 4 weeks for rape and up to 7 months for maize, whereas PCR analysis of composted transgenic maize revealed the presence of the transgene over a period of 22 months.

The effects of glyphosate, glufosinate, paraquat and paraquat-diquat on soil microbial activity and bacterial, archaeal and nematode diversity

“…Information concerning the effects of glufosinate on microbial community composition is limited. As seen in our study, recommended doses of glufosinate in the form of Basta and Liberty have been shown to have negligible effects on microbial community composition as represented by PLFA 18 and DNA fingerprinting 19 , respectively. For paraquat and paraquat-diquat, information concerning their effects on soil microbial community composition is even more limited.…”

“…For glufosinate, which is a chemical relative of glyphosate, some studies indicate that low-levels (≤10 mg/kg) exert significant positive and negative effects on the relative abundances of various bacterial taxa when applied as Basta 15 , 16 and Liberty 17 , while others demonstrate that similar application rates of Basta 18 and Liberty 19 have no effect on microbial community structure.…”

Already a short-term soils exposure to the field-rate glufosinate concentration significantly influences soil bacterial communities

“…E.g. Ernst et al (2008) detected no influence of Basta ® herbicide at a dose of 600 g per ha on soil microbial biomass in the field experiments. On the other hand, Griffiths et al (2008) in glasshouse experiment using the same herbicide dose as Ernst et al (2008) observed that glufosinate application in general altered the community level physiological profile of the microbial community and reduced both the soil basal respiration and the abundance of protozoa but, compared to other standard agricultural practices, the differences were relatively small.…”

Impact of Herbicides on Soil Biology and Function

“…However, Schmalenberger and Tebbe (2003) did not detect changes in the bacterial community structure after glufosinate application to conventional or transgenic herbicide-tolerant maize, using molecular methods. Likewise, Ernst et al (2008) found no impact on bacterial community structure when glufosinate (0.6 kg ha -1 ) was applied to glufosinate-resistant rape/maize. The contradictory nature of these results may be a consequence of different monitoring periods and environmental conditions, as Griffiths et al (2008) found altered microbial diversity (CLPP and ester-linked FAME) at 6 weeks after herbicide application but no differences at 12 weeks.…”

“…Nevertheless, the actual community structure had shifted at 60 d from controls in all acetochlor treatments (Xin-Yu et al, 2010). Applications of metazachlor (0.5 kg ha -1 ) also altered the PLFA community structure in the rhizosphere of non-transgenic canola (Ernst et al, 2008), but measurements were made at one unspecified time, so no assessment of resilience could be made. Pretilachlor (0.45 kg ha -1 ) had no significant impact on MBC or PLFA profiles in a rice paddy soil (Murata et al, 2004).…”