Table 1. EC50, resistance factor and associated phenotype of Didymella tanaceti isolates (n = 92) with known SDH substitutions.
| Isolatea | Substitutionb | Accession number | EC50c | RFd | Phenotypee | Boscalid concentrations tested (μg a.i./mL) | ||
|---|---|---|---|---|---|---|---|---|
| SdhB | SdhC | SdhD | ||||||
| 041–0002 | MK500737- MK500739 | 0.02 | 0.5 | S | 0, 0.001, 0.01, 0.05, 0.25, 0.5, 1.25 | |||
| 041–0032 | 0.04 | 0.9 | S | 0, 0.001, 0.01, 0.05, 0.25, 0.5, 1.25 | ||||
| 041–0034 | 0.05 | 1.3 | S | 0, 0.001, 0.01, 0.05, 0.25, 0.5, 1.25 | ||||
| 041–0047 | L88M | MK500740- MK500743 | 0.04 | 0.9 | S | 0, 0.001, 0.01, 0.05, 0.25, 0.5, 1.25 | ||
| 041–0049 | 0.09 | 2.2 | S | 0, 0.001, 0.01, 0.05, 0.25, 0.5, 1.25 | ||||
| 041–0076 | 0.04 | 1.0 | S | 0, 0.001, 0.01, 0.05, 0.25, 0.5, 1.25 | ||||
| 041–0077 | L88M | 0.04 | 0.9 | S | 0, 0.001, 0.01, 0.05, 0.25, 0.5, 1.25 | |||
| 041–0231 | 0.04 | 0.9 | S | 0, 0.001, 0.01, 0.05, 0.25, 0.5, 1.25 | ||||
| F50607A | 0.03 | 0.8 | S | 0, 0.001, 0.01, 0.05, 0.25, 0.5, 1.25 | ||||
| F50607B | 0.03 | 0.7 | S | 0, 0.001, 0.01, 0.05, 0.25, 0.5, 1.25 | ||||
| 041–0001 | H277Y | MK500757 | 27.60 | 673.2 | HR | 0, 2.5, 5, 10, 25, 50 | ||
| 041–0004 | H277Y | L88M | MK500758 | 15.90 | 387.8 | HR | 0, 2.5, 5, 10, 25, 50 | |
| 041–0009 | H277Y | 19.80 | 482.9 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0015 | H277Y | 19.40 | 473.2 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0022 | H277Y | 50.00 | 1219.5 | VHR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0041 | H277Y | 15.00 | 365.9 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0088 | H277Y | MK500760 | 17.30 | 422.0 | HR | 0, 2.5, 5, 10, 25, 50 | ||
| 041–0242 | H277Y | 12.90 | 314.6 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–1335 | H277Y | 2.87 | 70.0 | MR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–1338 | H277Y | 12.70 | 309.8 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0018 | H277R | 9.17 | 223.7 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0024 | H277R | MK500759 | 9.80 | 239.0 | HR | 0, 2.5, 5, 10, 25, 50 | ||
| 041–0031 | H277R | 5.41 | 132.0 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0252 | H277R | 2.56 | 62.4 | MR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0414 | H277R | 8.28 | 202.0 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0485 | H277R | 10.40 | 253.7 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0586 | H277R | 8.63 | 210.5 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0744 | H277R | 15.60 | 380.5 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0748 | H277R | L88M | MK500762 | 11.20 | 273.2 | HR | 0, 2.5, 5, 10, 25, 50 | |
| 041–1641 | H277R | 10.20 | 248.8 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0039 | I279V | 0.90 | 21.9 | MR | 0, 0.05, 0.25, 0.5, 1.25, 2.5 | |||
| 041–0227 | I279V | MK500761 | 0.38 | 9.3 | LR | 0, 0.05, 0.25, 0.5, 1.25, 2.5 | ||
| 041–0235 | I279V | 0.37 | 9.1 | LR | 0, 0.05, 0.25, 0.5, 1.25, 2.5 | |||
| 041–0253 | I279V | 0.48 | 11.8 | MR | 0, 0.05, 0.25, 0.5, 1.25, 2.5 | |||
| 041–0254 | I279V | 0.33 | 8.1 | LR | 0, 0.05, 0.25, 0.5, 1.25, 2.5 | |||
| 041–0267 | I279V | 1.87 | 45.6 | MR | 0, 0.05, 0.25, 0.5, 1.25, 2.5 | |||
| 041–0766 | I279V | 0.59 | 14.4 | MR | 0, 0.05, 0.25, 0.5, 1.25, 2.5 | |||
| 041–0902 | I279V | 0.45 | 11.0 | MR | 0, 0.05, 0.25, 0.5, 1.25, 2.5 | |||
| 041–0914 | I279V | 0.52 | 12.8 | MR | 0, 0.05, 0.25, 0.5, 1.25, 2.5 | |||
| 041–0136 | S73P | MK500751 | 19.90 | 485.4 | HR | 0, 0.5, 5, 10, 25, 50 | ||
| 041–0958 | S73P | 7.95 | 193.9 | HR | 0, 0.5, 5, 10, 25, 50 | |||
| 041–0989 | S73P | 6.22 | 151.7 | HR | 0, 0.5, 5, 10, 25, 50 | |||
| 041–0992 | S73P | 6.76 | 164.9 | HR | 0, 0.5, 5, 10, 25, 50 | |||
| 041–1029 | S73P | 20.90 | 509.8 | HR | 0, 0.5, 5, 10, 25, 50 | |||
| 041–0204 | G79R | MK500753 | 30.00 | 731.7 | HR | 0, 0.5, 5, 10, 25, 50 | ||
| 041–0245 | G79R | 31.50 | 768.3 | HR | 0, 0.5, 5, 10, 25, 50 | |||
| 041–0259 | G79R | 30.90 | 753.7 | HR | 0, 0.5, 5, 10, 25, 50 | |||
| 041–0814 | G79R/L88M | MK500756 | 46.10 | >1000 | VHR | 0, 0.5, 5, 10, 25, 50 | ||
| 041–0984 | G79R | 43.60 | >1000 | VHR | 0, 0.5, 5, 10, 25, 50 | |||
| 041–1039 | G79R | 23.90 | 582.9 | HR | 0, 0.5, 5, 10, 25, 50 | |||
| 041–1298 | G79R | 29.20 | 712.2 | HR | 0, 0.5, 5, 10, 25, 50 | |||
| CF196 | G79R | 21.30 | 519.5 | HR | 0, 0.5, 5, 10, 25, 50 | |||
| 041–0007 | H134R | MK500748 | >50 | >1000 | VHR | 0, 2.5, 5, 10, 25, 50 | ||
| 041–0016 | H134R/L88M | MK500749 | >50 | >1000 | VHR | 0, 2.5, 5, 10, 25, 50 | ||
| 041–0025 | H134R | 42.20 | 1029.3 | VHR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0027 | H134R | >50 | >1000 | VHR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0107 | H134R | >50 | >1000 | VHR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0188 | H134R/L88M | >50 | >1000 | VHR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0522 | H134R | 35.30 | 861.0 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0622 | H134R | 16.60 | 404.9 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–1255 | H134R | >50 | >1000 | VHR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–1345 | H134R | >50 | >1000 | VHR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0391 | H134Q | MK500754 | 3.0 | 71.9 | MR | 0, 2.5, 5, 10, 25, 50 | ||
| 041–0162 | S135R | MK500752 | 26.2 | 639.0 | HR | 0, 2.5, 5, 10, 25, 50 | ||
| 041–0328 | S135R | 16.2 | 395.1 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0358 | S135R | 13.5 | 329.3 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0370 | S135R | 25.6 | 624.4 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0397 | S135R | 25.1 | 612.2 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0455 | S135R | 13.4 | 326.8 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0784 | S135R/L88M | MK500755 | >50 | >1000 | VHR | 0, 2.5, 5, 10, 25, 50 | ||
| 041–1344 | S135R | 13.5 | 329.3 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–1350 | S135R | 29.4 | 717.1 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| CF2 | S135R | 32.9 | 802.4 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0132 | H134Q/S135R | MK500750 | 24.30 | 592.7 | HR | 0, 2.5, 5, 10, 25, 50 | ||
| 041–0163 | H134Q/S135R | 26.70 | 651.2 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0193 | H134Q/S135R | 25.50 | 622.0 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0201 | H134Q/S135R | 23.60 | 575.6 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0875 | H134Q/S135R | 16.40 | 400.0 | HR | 0, 2.5, 5, 10, 25, 50 | |||
| 041–0035 | D112E | MK500743 | 5.52 | 134.6 | HR | 0, 0.5, 1.25, 2.5, 5, 10 | ||
| 041–0036 | L88M | D112E | MK500744 | 4.88 | 119.0 | HR | 0, 0.5, 1.25, 2.5, 5, 10 | |
| 041–0038 | L88M | D112E | MK500745 | 2.80 | 68.3 | MR | 0, 0.5, 1.25, 2.5, 5, 10 | |
| 041–0335 | D112E | 4.63 | 112.9 | HR | 0, 0.5, 1.25, 2.5, 5, 10 | |||
| 041–0340 | D112E | 9.22 | 224.9 | HR | 0, 0.5, 1.25, 2.5, 5, 10 | |||
| 041–0435 | L88M | D112E | MK500747 | 3.56 | 86.8 | MR | 0, 0.5, 1.25, 2.5, 5, 10 | |
| 041–0439 | D112E | 2.82 | 68.8 | MR | 0, 0.5, 1.25, 2.5, 5, 10 | |||
| 041–1282 | D112E | 1.88 | 45.9 | MR | 0, 0.5, 1.25, 2.5, 5, 10 | |||
| 041–1333 | D112E | 1.30 | 31.7 | MR | 0, 0.5, 1.25, 2.5, 5, 10 | |||
| F50403B | D112E | 3.02 | 73.7 | MR | 0, 0.5, 1.25, 2.5, 5, 10 | |||
| 041–0297 | H122R | MK500746 | 9.29 | 226.6 | HR | 0, 0.5, 5, 10, 25, 50 | ||
| 041–1111 | H122R | 32.20 | 785.4 | HR | 0, 0.5, 5, 10, 25, 50 | |||
| 041–1130 | H122R | 21.00 | 512.2 | HR | 0, 0.5, 5, 10, 25, 50 | |||
| CF149 | H122R | 39.10 | 953.7 | HR | 0, 0.5, 5, 10, 25, 50 | |||
a Didymella tanaceti isolates stored in the Tasmanian Institute of Agriculture fungal collection, Tasmania, Australia. All isolates originally recovered from pyrethrum leaves.
b Substitution identified via high resolution melt assay and confirmed by sequencing.
c EC50 = estimated boscalid concentration (μg/a.i./mL) to reduce radial growth by 50% of the non-amended controls. Calculated using logistic regression of the relative growth against log10 of the boscalid concentration.
d Resistance Factor (RF) = EC50X/EC50WT, where EC50X is the EC50 value of the isolate being examined, and EC50WT is the average EC50 value of the baseline isolates (WT).
e Boscalid phenotype based on the interpretation of RF values; S = sensitive (RF ≤ 3) LR = low resistance (3 > RF ≤ 10), MR = moderate resistance (10 > RF ≤ 100), HR = high resistance (100 > RF ≤ 1000) and VHR = very high resistance (RF >1000).