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Published on: June 22, 2017
Multiple point mutations in PsORP1 gene conferring different resistance levels to oxathiapiprolin confirmed using
Jianqiang Miao1, Xiaofei Liu1, Guixiang Li1
1State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, China.
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 < 80. Phenotype assays revealed that the most highly resistant transformants showed enhanced or similar pathogenicity, oospore production, and cyst gemination. However, most transformants displayed decreased sporangia and zoospore production compared with parental wild-type P6497.
Conclusion:
This study demonstrated that L733W, S768F, S768Y, N837Y, N837F, P861H, L863W, and I877Y in PsORP1 confer high oxathiapiprolin resistance in P. sojae.
