. 2019 Jul 10;10:1590. doi: 10.3389/fmicb.2019.01590

TABLE 2.

Production of different phenazines by P. chlororaphis 30-84 promotes root growth of wheat seedlings in natural soil.

Strain Derivative	Cycle 1 Root dry weight (mg)	Cycle 2 Root dry weight (mg)	Cycle 3 Root dry weight (mg)	Cycle 4 Root dry weight (mg)	Cycle 5 Root dry weight (mg)
30-84Enh	1.15 ± 0.19^a	0.96 ± 0.13^a	0.92 ± 0.15^a	0.92 ± 0.11^a	1.00 ± 0.13^a
30-84WT	1.22 ± 0.11^a	1.13 ± 0.14^a	0.97 ± 0.08^a	0.94 ± 0.04^a	0.87 ± 0.08^a
30-84MS	1.14 ± 0.14^a	1.14 ± 0.14^a	1.18 ± 0.16^a	0.97 ± 0.07^a	0.98 ± 0.07^a
30-84H	0.89 ± 0.14^ab	0.79 ± 0.14^ab	0.71 ± 0.09^ab	0.89 ± 0.14^a	0.85 ± 0.06^a
30-84ZN	0.82 ± 0.07^b	0.69 ± 0.03^b	0.68 ± 0.04^b	0.60 ± 0.07^b	0.59 ± 0.03^b

Wheat seedlings were pre-germinated 3 days and then grown in cones containing natural (not autoclaved) soil inoculated either with 30-84Enh, 30-84WT, 30-84MS (produces pyocyanin), 30-84H (produces phenazine-1-carboxamide), or 30-84ZN (no phenazine control). Seedlings were grown under well-watered conditions for 21 days, and 6 plants per treatment were harvested at the end of each plant/harvest cycle. Bacterial populations on roots were determined by serial dilution plating on LB amended with rifampicin and cycloheximide, and root dry weight biomass was determined. For the plants not used in the CFU estimations, shoots were removed at the soil surface level. The soil and remaining root systems were homogenized and reused as planting medium, as previously described (Yu et al., 2018a). Newly germinated wheat seedlings were re-planted into the processed soil and the plant/harvest/sample cycle was repeated 5 times. Data are the mean dry weight biomass and standard error (N = 6). For each plant/harvest cycle, treatments with the same letter are not significantly different.