Aims: In a field study, the effects of treatments of glyphosate-based herbicides (GBHs) in soil, alone and in combination with phosphate fertilizer, were examined on the performance and endophytic microbiota of garden strawberry. 

Methods and results: The root and leaf endophytic microbiota of garden strawberries grown in GBH-treated and untreated soil, with and without phosphate fertilizer were analyzed. Next, bioinformatics analysis on the type of 5-enolpyruvylshikimate-3-phosphate synthase enzyme was conducted to assess the potential sensitivity of strawberry-associated bacteria and fungi to glyphosate, and to compare the results with field observations. GBH treatments altered the abundance and/or frequency of several operational taxonomic units (OTUs), especially those of root-associated fungi and bacteria. These changes were partly related to their sensitivity to glyphosate. Still, GBH treatments did not shape the overall community structure of strawberry microbiota or affect plant performance. Phosphate fertilizer increased the abundance of both glyphosate-resistant and glyphosate-sensitive bacterial OTUs, regardless of the GBH treatments.

Conclusions: These findings demonstrate that although the overall community structure of strawberry endophytic microbes is not affected by GBH use, some individual taxa are.

Significance and impact of study: Agrochemical residues in soil can shape the endophytic microbiota in crop plants.

Strawberry plantlets grown in greenhouse were planted to the experimental fields three weeks after glyphosate-based herbicide application in June 2019. The number of leaves and length of produced runners were measured in mid-August 2019. Samples for micobiome studies were collected in August 2019 from root and leaves of garden strawberry grown in glyphosate, phosphate fertilizer and glyphosate combined with phosphate fertilizer treated fields. The tissue samples were then processed for DNA extraction, PCR and high-throughput sequencing.