Preparation of DNA mixtures
Two Rlt strains (SM3 and SM170C) were chosen based on theirrecA , rpoB , nodA, and nodD sequence
divergence, with a minimum of 3 base pair differences in the amplicon
region required for each gene. Strains were grown on Tryptone Yeast agar
(28°C, 48hrs). Culture was resuspended in 750ul of the DNeasy Powerlyzer
PowerSoil DNA isolation kit (QIAGEN, USA) and DNA was extracted
following the manufacturer’s instructions. DNA sample concentrations
were calculated using QuBit (Thermofisher Scientific Inc., USA). DNA
samples of the two strains were diluted to the same concentration and
mixed in various ratios (Supplementary Table S1) .