Metagenomic survey of the bacterial communities in the rhizosphere of three Andean tuber crops

Abstract

Microbes colonizing the rhizosphere are important drivers of plant health, supplying nutrients and antagonizing pathogens, among other beneficial activities. Tubers are important staple crops in the Andean highlands, produced by thousands of small-farmers and consumed by millions. Here we report the composition of the bacterial communities colonizing the rhizospheres of three Andean tuber crops (ATCs), namely oca (Oxalis tuberosa), ullucu (Ullucus tuberosus) and mashua (Tropaeolum tuberosum). We used high throughput sequence analysis of 16S rRNA genes to describe the bacterial diversity of rhizospheric soils associated to thee crops. Between 4862 and 5080 OTUs were exclusively detected in each one of the ATCs’ rhizospheres; the majority of the 100 most abundant OTUs belonged to the Bacteroidetes and Proteobacteria phyla. Beta diversity indices revealed a low similarity between the three communities, suggesting differences in their specific composition. Only 566 bacterial OTUs were shared by all three tuber’s rhizospheres and absent from the surrounding bulk soil. Apart from studies in potato, this is the first report concerning the diversity and abundance of bacterial taxa associated with the rhizosphere of other important and traditional ATCs.