TABLE 2.
Limit of detection of real-time PCR analyses of pure culture cells of Xanthomonas arboricola pv. pruni strain ISPaVe B4 in cell suspensions and in spiked samples
| Sample | Heat treatment |
DNA extraction |
||||
|---|---|---|---|---|---|---|
| CFU ml−1 | Mean E ± SDa | Avg CT ± SDb | CFU ml−1 | Mean E ± SDa | Avg CT ± SDb | |
| Bacteria | 103 | 2.11 ± 0.11 | 33.95 ± 3.01 | 102 | 1.86 ± 0.05 | 39.28 ± 2.28 |
| Spiked washed leaves | ||||||
| Peach | 102 | 1.92 ± 0.02 | 40.62 ± 3.16 | 102 | 1.92 ± 0.02 | 36.06 ± 0.26 |
| Almond | 102 | 1.95 ± 0.17 | 37.33 ± 0.86 | 102 | 1.88 ± 0.04 | 36.6 ± 0.55 |
| GF-677 | 102 | 2.03 ± 0.02 | 38.84 ± 2.10 | 102 | 1.98 ± 0.08 | 36.42 ± 1.61 |
| Japanese plum | 105 | 1.62 ± 0.02 | 33.41 ± 0.82 | 102 | 1.96 ± 0.05 | 37.36 ± 0.11 |
| Spiked comminuted leaves | ||||||
| Peach | 104 | 1.82 ± 0.24 | 27.80 ± 1.93 | 102 | 1.90 ± 0.05 | 34.54 ± 1.05 |
| Almond | 103 | 1.97 ± 0.08 | 33.37 ± 0.81 | 102 | 1.98 ± 0.02 | 34.25 ± 1.13 |
| GF-677 | 103 | 2.02 ± 0.12 | 33.49 ± 0.87 | 102 | 1.99 ± 0.09 | 34.09 ± 1.20 |
| Japanese plum | —c | 1.62 ± 0.02 | —c | 102 | 2.11 ± 0.05 | 39.78 ± 2.35 |
a
E is the average efficiency of amplification, calculated using the formula E = 10[−1/k], where k is the regression line slope. Means and standard deviations were calculated from at least two regression lines calculated from at least two PCRs per bacterial concentration and two independent assays.
b
Average CT values were calculated for at least three PCRs from the lowest bacterial concentration detected.
c
—, no fluorescence above the threshold was recorded.