Suppression treatment differentially influences the microbial community and the occurrence of broad host range plasmids in the rhizosphere of the model cover crop Avena sativa L.

ALLEGRINI MARCO; ZABALOY M. CELINA; GÓMEZ ELENA; SMALLA KORNELIA

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2019 p. 1 - 29

1932-6203

Cover crop suppression with glyphosate-based herbicides (GBHs) represents a commonagricultural practice. The objective of this study was to compare rhizospheric microbialcommunities of A. sativa plants treated with a GBH relative to the mechanical suppression(mowing) in order to assess their differences and the potential implications for soil processes.Samples were obtained at 4, 10, 17 and 26 days post-suppression. Soil catabolicprofiling and DNA-based methods were applied. At 26 days, higher respiration responsesand functional diversity indices (Shannon index and catabolic evenness) were observedunder glyphosate suppression and a neat separation of catabolic profiles was detected inmultivariate analysis. Sarcosine and Tween 20 showed the highest contribution to this separation.Metabarcoding revealed a non-significant effect of suppression method on eitheralpha-diversity metrics or beta-diversity. Conversely, differences were detected in therelative abundance of specific bacterial taxa. Mesorhizobium sequences were detected inhigher relative abundance in glyphosate-treated plants at the end of the experiment whilethe opposite trend was observed for Gaiella. Quantitative PCR of amoA gene from ammonia-oxidizing archaea showed a lower abundance under GBH suppression again at 26days, while ammonia-oxidizing bacteria remained lower at all sampling times. Broad hostrange plasmids IncP-1β and IncP-1ε were exclusively detected in the rhizosphere of glyphosate-treated plants at 10 days and at 26 days, respectively. Overall, our study demonstratesdifferential effects of suppression methods on the abundance of specific bacterial taxa, onthe physiology and mobile genetic elements of microbial communities while no differenceswere detected in taxonomic diversity.