TABLE 4.

Number of reads and OTUs derived from NGS analysis of xylem sap microbiota from DNA samples extracted with the PowerPlant protocol, amplified with four PCR protocols, and taxonomic assignment using the Silva 132 reference database.

Reads/OTUs	PCR-2	PCR-3	N1PCR1*	N2PCR1*
	967F-1193R	799F-1193R	799F-1193R	967F-1391R
Number of reads (Mean/sample)	6178	3867	3175	2376
Unassigned Reads (%)	2.06	2.89	12.09	6.58
Plant (chloroplast + mitochondria) reads (%)	56.75	0	0	0
Bacterial reads (%)	41.19	97.11	87.91	93.42
OTUs at the Phylum level	13	10	8	7
OTUs at the Class level	27	17	13	13
OTUs at the Order level	52	47	39	39
OTUs at the Family level	94	93	68	70
OTUs at the Genus level	154	162	100	107
Total Assigned OTUs	233	242	141	156

*N1PCR1 and N2PCR1 were nested PCRs that used as DNA template the amplification product obtained with primers 799F + 1193R (PCR1) (Table 2).

NGS, next-generation sequencing; OTU, operational taxonomic unit.