Bacterial operational taxonomic units (OTUs) identified in this study.

aBacteria were grouped into OTUs defined by 97% sequence identity at the 16S rRNA gene (732–744 bp).bBacteria were grouped into OTUs defined by 99% sequence identity at the 16S rRNA gene (732–744 bp).cBased on BLAST analysis (August 2012). Only closest matches to named species are reported.dNumber of isolates recovered in this study. 24 isolates could only be identified to the family level, including members of the Microbacteriaceae (18), Staphylococcaceae (3), Streptomycetaceae (2) and Pseudomonadaceae (1).eNumber of plant populations in which the corresponding OTUs were recorded.