Multiple point mutations in PsORP1 gene conferring different resistance levels to oxathiapiprolin confirmed using CRISPR–Cas9 in Phytophthora sojae

BACKGROUND Oxathiapiprolin is among the first commercial oxysterol‐binding protein inhibitors (OSBPIs) developed by DuPont Corporation and shows excellent activity against plant‐pathogenic oomycetes. Although more than 21 target site mutations have been identified in insensitive oomycetes, only G770V, G839W, and ΔN837 have been verified to confer oxathiapiprolin resistance in Phytophthora capsici or P. sojae. The effect of other mutations on OSBPIs sensitivity requires urgent investigation. RESULTS P. sojae transformants containing 16 mutations of PsORP1 were recovered using the CRISPR–Cas9 system. Transformants containing L733W, S768F, S768Y, N837Y, N837F, P861H, L863W, or I877Y showed high oxathiapiprolin resistance, with resistant factors (RFs) > 3000. Point mutations S768K, S768I, G770L, G770P, G770A, ΔG818/F819, N837I, and I877F exhibited low resistance, with RFs