Comparison of the Rhizosphere Bacterial Communities of Zigongdongdou Soybean and a High-Methionine Transgenic Line of This Cultivar

Abstract

Previous studies have shown that methionine from root exudates affects the rhizosphere bacterial population involved in soil nitrogen fixation. A transgenic line of Zigongdongdou soybean cultivar (ZD91) that expresses Arabidopsis cystathionine γ-synthase resulting in an increased methionine production was examined for its influence to the rhizosphere bacterial population. Using 16S rRNA gene-based pyrosequencing analysis of the V4 region and DNA extracted from bacterial consortia collected from the rhizosphere of soybean plants grown in an agricultural field at the pod-setting stage, we characterized the populational structure of the bacterial community involved. In total, 87,267 sequences (approximately 10,908 per sample) were analyzed. We found that Acidobacteria, Proteobacteria, Bacteroidetes, Actinobacteria, Chloroflexi, Planctomycetes, Gemmatimonadetes, Firmicutes, and Verrucomicrobia constitute the dominant taxonomic groups in either the ZD91 transgenic line or parental cultivar ZD, and that there was no statistically significant difference in the rhizosphere bacterial community structure between the two cultivars.

High-methionine soybean has no significant effect on nitrogen-transforming bacteria in rhizosphere soil

“…Each cultivar had four randomized blocks, and soybean was maintained in accordance with the typical agronomic practices in Southwestern China. The rhizosphere soil samples were collected at four growth stages: seedling stage (SS); flowering stage (FS); pod-setting stage (PS) and maturitysetting stage (MS), as previously described (Liang et al 2014(Liang et al , 2015.…”

“…Fragments of these two genes were amplified using the primer pairs nifH-F/nifH-R (Rösch et al 2002) for the nifH gene and amoA-1F/amoA-2R (Rotthauwe et al 1997) for the amoA-AOB gene. qPCR was performed according to our previously described protocols (Liang et al 2014). The R 2 values of all these standard curves were higher than 0.99.…”

“…DNA isolated from soil samples (3 randomly selected samples per cultivar) at the pod-setting stage was used for the PCR amplification (Liang et al 2014). Fragments of the nifH (~440 bp) and amoA-AOB (~500 bp) genes were amplified using the primer pairs described above.…”

“…Our previous studies found that the transgenic highmethionine soybean cv. ZD91 had no significant impact on rhizosphere bacterial, arbuscular mycorrhizal fungal community structures and functional diversity of the rhizosphere microorganisms (Liang et al 2014(Liang et al , 2015(Liang et al , 2016. However, the knowledge of the cv.…”

High-methionine soybean has no adverse effect on functional diversity of rhizosphere microorganisms

“…As the safety assessment of GM crops should be case by case (Liang et al 2015), the question arises whether transgenic soybean plants with altered content of methionine will affect soil microbial community catabolic diversity. Although transgenic highmethionine soybean ZD91 was reported to have no significant impact on rhizosphere bacterial and arbuscular mycorrhizal fungal communities structures (Pu et al 2012, Liang et al 2014, knowledge on the effect of GM soybean ZD91 on functional diversity and activity of microbial communities in rhizosphere soil remains fairly limited so far. Therefore, the objective of this study was to investigate the effects of GM soybean ZD91 on rhizosphere microbial communities function by the Biolog-ECO plate, and to provide some information on the risk assessment of the GM soybean ZD91.…”