Resistance Risk and Novel Resistance-Related Point Mutations in Target Protein PiORP1 of Fluoxapiprolin in Phytophthora infestans

Abstract

Fluoxapiprolin is a new oxysterol binding protein inhibitor (OSBPI), which showed excellent inhibitory activity to plant pathogenic oomycetes. Its resistance risk and mechanism in Phytophthora infestans are unclear. In the current study, the sensitivities of 103 P. infestans isolates to fluoxapiprolin were investigated, and a unimodal distribution with a mean EC 50 value of 0.00035 μg/mL was observed. Four types of resistant mutants, with a resistance factor from 14 to more than 1000, and point mutations S768I+N837I, S768I+L860I, S768I, and I877F in PiORP1, were acquired using fungicide adaption. The fitness of the mutants was similar to or lower than that of the corresponding parental isolate. Positive cross-resistance was detected between fluoxapiprolin and oxathiapiprolin. The point mutations were verified in P. sojae homologue positions using the CRISPR/Cas9 genome editing system. Transformants containing S768I+N837I or S768I+L860I, showed high fluoxapiprolin resistance (RF > 1000). In conclusion, the risk of P. infestans resistance to fluoxapiprolin is moderate, and novel point mutation types S768I+N837I or S768I+L860I could cause high fluoxapiprolin resistance in P. infestans.

Evaluation of SYP‐34773's resistance risk and its impact on the activity of mitochondrial respiratory electron transport chain complex I in Phytophthora litchii

“…Once the growth on the control plates covered 75% of the temporary culture medium surface at a temperature of 25 °C, the vertical diameter of each colony was measured. Subsequently, the EC 50 for each isolate was calculated, using the method described in our previous study 20 …”

“…Subsequently, the EC 50 for each isolate was calculated, using the method described in our previous study. 20 2.4 Selection of SYP-34773-resistant mutants of P. litchii Five P. litchii isolates (HN10-2, GX10-1, GXBL-31, GXBL-26 and GXBL-10) were chosen at random for the process of SYP-34773 induction. Mycelial plugs (5 mm diameter) were excised from 5-day-old V8 colonies and transferred onto V8 plates with 50 μg mL −1 SYP-34773.…”

Rationally Designed Novel Antimicrobial Peptides Targeting Chitin Synthase for Combating Soybean Phytophthora Blight

“…Notably, only a few drugs and one cyclic antifungal peptide from marine fungi have shown inhibitory effects against soybean phytophthora blight [ 21 , 22 , 23 , 24 ]. Interestingly, Fluoxapiprolin, Oxzthiapiprolin, and Ethaboxam, developed by Bayer and DuPont (Wilmington, DE, USA), have demonstrated the ability to inhibit the growth of P. sojae by targeting spores and mycelium ( Figure 1 ) [ 25 , 26 , 27 , 28 ]. However, it is worth noting that these compounds belong to the thiazole class, and mutations in the single dominant genes (Rps) and β-tubulin have been identified as potential causes of drug resistance [ 29 ].…”