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Knockout of the lignin pathway gene BnF5H decreases the S/G lignin composition ratio and improves S. sclerotiorum resistance in B. napus
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  • Yanru Cao,
  • Xingying Yan,
  • Shuyao Ran,
  • John Ralph,
  • Rebecca Smith,
  • Xueping Chen,
  • Cunmin Qu,
  • Jiana Li,
  • Liezhao Liu
Yanru Cao
Southwest University
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Xingying Yan
Southwest University
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Shuyao Ran
Southwest University
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John Ralph
University of Wisconsin-Madison
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Rebecca Smith
University of Wisconsin-Madison
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Xueping Chen
Southwest University
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Cunmin Qu
Southwest University
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Jiana Li
Southwest University
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Liezhao Liu
Southwest University
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Abstract

Ferulate-5-hydroxylase (F5H) is a key enzyme involved in the conversion of the guaiacyl monolignol (G-monolignol) to the syringyl monolignol (S-monolignol) in angiosperms. The monolignol ratio has been proposed to affect biomass recalcitrance and the resistance to plant disease. Sclerotinia sclerotiorum (S. sclerotiorum) stem rot of Brassica napus (B. napus) causes heavy damage in oilseed rape production. To date, there is no information about the effect of the lignin monomer ratio on the resistance to S. sclerotiorum in B. napus. Four dominantly expressed BnF5H genes were knocked out by CRISPR/Cas9 simultaneously in B. napus, and the f5h mutant KO-7 was generated. The S/G lignin composition ratio was decreased compared to that of the wild type (WT) based on the results of MÓ“ule staining and 2D-NMR profiling. The resistance to S. sclerotiorum in stems and leaves increased in KO-7. Furthermore, we found that the stem strength of KO-7 was significantly increased compared to that of the WT. Collectively, for the first time, we demonstrate that knockout of the lignin pathway gene F5H decreases the S/G ratio, improves S. sclerotiorum resistance in B. napus, and increases stem strength.