TABLE 2.
The screening of plant growth promotion traits in vitro and in planta (germination blotter or soil substrate assays).
|
In vitro assays |
Germination blotter assay |
Soil substrate assay |
|||||||||||||
| Treatment | IAA production (μg/mL) ± SD | Phosphate solubilization activity | Siderophore production (mm) ± SD | Chitinase activity (mm) ± SD | Starch hydrolysis | Nitrate reduction |
Growth at high salt concentration |
Germinated seeds (%) per blotter ± SD | Root length (mm) per plant ± SD | Shoot length (mm) per plant ± SD | Root dried weight (mg) per plant ± SD | Shoot dried weight (mg) per plant ± SD | Shoot length (mm) per plant ± SD | Shoot dried weight (mg) per plant ± SD | |
| 3.5% | 7% | ||||||||||||||
| Water | / | / | / | / | / | / | / | / | 98.13 ± 3.96 | 176.50 ± 32.51 | 135.43 ± 17.57 | 25.95 ± 6.23 | 12.45 ± 3.79 | 285.95 ± 32.79 | 57.50 ± 14.05 |
| control | |||||||||||||||
| DEF06 | 0.00 ± 0.07 | + | 10.75 ± 3.18 | 1.00 ± 0.00 | + | + | + | – | 93.75 ± 5.17 | 193.17 ± 30.66 | 127.78 ± 26.58 | 23.09 ± 5.90 | 12.19 ± 2.12 | nt | nt |
| DEF07 | 1.36 ± 0.29 | – | – | 6.00 ± 1.75 | + | – | + | + | 95.00 ± 7.56 | 173.88 ± 22.31 | 136.06 ± 12.54 | 22.86 ± 8.22 | 11.04 ± 2.23 | 287.13 ± 27.03 | 51.44 ± 10.29 |
| DEF08 | 0.00 ± 0.09 | – | – | 0.5 ± 0.71 | + | + | + | + | 91.25 ± 11.26 | 174.33 ± 27.89 | 125.60 ± 10.19 | 24.80 ± 7.05 | 21.24 ± 12.22 | 309.40 ± 28.10 | 44.28 ± 12.70 |
| DEF09 | 2.50 ± 0.04 | – | – | 1.58 ± 0.80 | – | + | + | + | 97.50 ± 4.63 | 118.13 ± 42.97∗ | 132.63 ± 13.62 | 25.29 ± 6.29 | 14.08 ± 4.40 | 307.10 ± 21.20 | 62.20 ± 7.91 |
| DEF13 | 0.00 ± 1.74 | – | – | 5.58 ± 2.65 | – | + | + | + | 87.50 ± 11.65 | 199.00 ± 14.67 | 131.56 ± 15.50 | 28.35 ± 6.67 | 9.27 ± 4.05 | nt | nt |
| DEF14 | 0.47 ± 0.65 | – | – | 2.17 ± 1.04 | + | + | + | + | 93.75 ± 7.44 | 168.93 ± 22.21 | 130.00 ± 21.84 | 23.61 ± 6.36 | 10.51 ± 2.39 | nt | nt |
| DEF15 | 0.85 ± 1.86 | – | – | 1.08 ± 0.95 | + | + | + | + | 97.50 ± 4.63 | 169.22 ± 21.17 | 122.00 ± 27.86 | 25.85 ± 5.54 | 10.73 ± 1.85 | nt | nt |
| DEF16 | 0.71 ± 0.86 | – | – | 1.25 ± 1.09 | + | – | + | + | 96.25 ± 5.17 | 143.00 ± 28.40 | 125.30 ± 17.42 | 25.44 ± 5.86 | 10.76 ± 1.95 | nt | nt |
| DEF17 | 0.00 ± 0.32 | + | 3.50 ± 0.70 | 3.58 ± 0.52 | + | + | + | – | 90.00 ± 5.34 | 143.42 ± 52.81 | 131.79 ± 16.79 | 25.92 ± 6.55 | 9.54 ± 1.80∗ | nt | nt |
| DEF18 | 0.00 ± 0.03 | – | 4 ± 0.70 | 2.12 ± 0.53 | + | + | + | + | 97.50 ± 4.63 | 166.06 ± 39.08 | 122.72 ± 25.31 | 31.03 ± 6.44 | 12.45 ± 1.60 | nt | nt |
| DEF19 | 0.96 ± 0.48 | – | – | 6.41 ± 1.38 | + | – | + | + | 100.00 ± 0.00 | 161.65 ± 23.05 | 119.76 ± 15.88 | 26.91 ± 5.81 | 9.76 ± 2.07 | 301.47 ± 23.92 | 52.39 ± 10.42 |
| DEF20 | 0.00 ± 0.21 | – | – | 3.42 ± 2.45 | – | – | + | – | 100.00 ± 0.00 | 155.39 ± 18.76 | 128.28 ± 16.60 | 22.09 ± 5.48 | 10.08 ± 2.06 | 269.00 ± 31.86 | 46.49 ± 8.62 |
| DEF21 | 1.03 ± 1.01 | + | – | 5.67 ± 0.63 | + | + | + | + | 97.50 ± 4.63 | 152.17 ± 38.13 | 123.83 ± 22.56 | 30.01 ± 5.84 | 11.75 ± 2.89 | nt | nt |
| DEF31 | 1.17 ± 0.73 | – | – | 1.00 ± 0.00 | + | – | + | + | 98.75 ± 3.53 | 169.00 ± 21.05 | 132.79 ± 9.99 | 23.56 ± 5.31 | 10.36 ± 1.84 | nt | nt |
| DEF33 | 7.51 ± 0.00 | – | – | 3.17 ± 0.58 | + | – | – | – | 98.75 ± 3.53 | 151.47 ± 25.31 | 133.24 ± 14.57 | 24.86 ± 6.39 | 10.87 ± 2.23 | nt | nt |
| DEF39 | 1.60 ± 0.04 | – | – | 1.00 ± 0.00 | + | + | + | + | 100.00 ± 0.00 | 147.12 ± 30.20 | 112.53 ± 19.69∗ | 19.71 ± 7.00 | 9.93 ± 1.93 | 302.57 ± 14.11 | 68.21 ± 10.96 |
| DEF40 | 0.00 ± 0.13 | – | – | 1.12 ± 0.18 | + | + | + | + | 98.75 ± 3.53 | 142.74 ± 32.36 | 110.58 ± 20.13∗ | 22.51 ± 4.75 | 10.02 ± 2.37 | nt | nt |
| DEF41 | 0.00 ± 0.03 | – | – | 1.33 ± 0.58 | – | – | + | + | 100.00 ± 0.00 | 126.94 ± 21.77∗ | 114.78 ± 23.84∗ | 30.86 ± 3.58 | 12.75 ± 1.31 | nt | nt |
| DEF46 | 1.12 ± 0.10 | – | 36.50 ± 0.00 | 2.66 ± 2.02 | + | – | + | – | 98.75 ± 3.53 | 139.78 ± 31.31∗ | 105.50 ± 21.61∗ | 28.45 ± 7.13 | 10.45 ± 1.75 | nt | nt |
| DEF47 | 0.00 ± 0.13 | – | – | 1.83 ± 0.63 | + | – | + | + | 93.75 ± 14.08 | 105.00 ± 17.13∗ | 108.75 ± 10.88∗ | 25.38 ± 8.31 | 10.04 ± 2.94 | 312.13 ± 23.32 | 53.04 ± 11.69 |
| DEF48 | 1.70 ± 0.02 | – | – | 7.33 ± 1.89 | + | – | + | + | 100.00 ± 0.00 | 133.90 ± 40.73∗ | 109.60 ± 22.38∗ | 23.13 ± 4.75 | 11.70 ± 2.60 | 311.55 ± 24.61 | 48.84 ± 9.65 |
Underlined are the strains that were not originally isolated as endophytes. ∗Indicates significant difference (P < 0.05) from the control assessed with Dunn’s test and Bonferroni correction for multiple comparison. nt Not tested. SD Standard Deviation. +, halo width 1 mm; −, not active. The growth at high salt concentration were compared to control plates (+ grown like control plates; – not grown).