Sterol demethylation inhibitor fungicide resistance in Colletotrichum siamense from chili is caused by mutations in CYP51A and CYP51B

Table 6 Sensitivity of the five genotype replacement mutants to tebuconazole, difenoconazole, prochloraz, and propiconazole in Colletotrichum siamense

Strain	Tebuconazole		Difenoconazole		Prochloraz		Propiconazole
Strain	EC₅₀ (mg/L)^a	RF^b	EC₅₀ (mg/L)	RF	EC₅₀ (mg/L)	RF	EC₅₀ (mg/L)	RF
Zz14	0.039 ± 0.0036d	–	0.018 ± 0.0013e	–	0.026 ± 0.0025f	–	0.065 ± 0.0016d	–
Zz17	0.042 ± 0.0012d	–	0.015 ± 0.002e	–	0.027 ± 0.0012f	–	0.063 ± 0.0023d	–
Genotype I	0.68 ± 0.024c	16.79	0.14 ± 0.015d	8.48	0.030 ± 0.0043e	1.13	0.32 ± 0.045c	5.00
Genotype II	2.04 ± 0.22a	50.37	0.15 ± 0.023d	9.09	0.091 ± 0.0033a	3.43	0.83 ± 0.016a	12.96
Genotype III	1.27 ± 0.17b	31.36	0.89 ± 0.81a	53.94	0.075 ± 0.0016b	2.83	0.53 ± 0.033b	8.28
Genotype IV	1.38 ± 0.37b	34.07	0.48 ± 0.035b	29.09	0.048 ± 0.0052c	1.81	0.33 ± 0.025c	5.15
Genotype V	0.72 ± 0.023c	17.78	0.32 ± 0.014c	19.39	0.039 ± 0.0012d	1.47	0.31 ± 0.061c	4.84

^aValues are the means ± standard deviations from three replicate experiments. Different letters indicate significant differences according to the Fisher’s LSD test at P = 0.05. ^bRF (resistance factor) = EC₅₀ value (resistant isolate)/EC₅₀ value (sensitive isolate)