design: Xylem sap from six plants per species was extracted by centrifuging 1.5 cm branch segments for 20 min at 16 000 g. DNA was extracted using a modified Wizard Genomic DNA Purification Kit (Promega). Briefly, up to 1.5 mL of sap was lysed at 65 C for 15 min, treated with RNase at 37 C for 5 min, and proteins were precipitated before DNA recovery by isopropanol precipitation and ethanol washing. Pellets were rehydrated at 65 C for 1 h, and DNA quality and concentration were verified using a NanoDrop spectrophotometer (Thermo Fisher Scientific). Bacterial 16S rRNA gene fragments were amplified using primers 27f and 1492r (Weisburg et al., 1991), purified with Agencourt AMPure XP beads (Beckman Coulter), and sequenced on an Illumina MiSeq platform (2 x 250 bp) targeting the V1V3 (27f/534r) and V3V4 (341f/805r) hypervariable regions.