Unravelling the composition of soil belowground microbial community before sowing transgenic cotton

Abstract

Soils harbour enormously diverse bacterial communities that interact specifically with plants generating beneficial interactions between them. This study was the first approach to assess bacterial communities before sowing with three cotton genotypes, including both transgenic and conventional ones. The structure of bacterial communities was identified using the next generation sequencing analysis, ion torrent PGM (Personal Genome Machine™) sequencer technology, based on the V2–V3 16S rRNA gene region. Quantitative insights into microbial ecology pipeline were used to identify the structure and diversity of bacterial communities in bulk soil samples collected in the northeast of Mexico. Bulk soil textures and chemical properties, including most nutrients, were homogeneous in these bulk soil samples. Relative abundance analysis showed similar bacterial community structures. Dominant taxonomic phyla were Proteobacteria, Firmicutes, Acidobacteria, Actinobacteria, Gemmatimonadetes and Bacteroidetes, whereas the main families were Bacillaceae, Chitinophagaceae and Rhodospirillaceae with an abundance average of BS1 (bulk soil sample), BS2 and BS3 (24.85, 19.74 and 19.71%, respectively). Alpha diversity analysis showed a high diversity (Shannon and Simpson index) and a large value of the observed species found in bulk soils samples. These results allowed establishing the previous bacterial structural community in an unused soil before sowing it with a transgenic crop for the first time.