Mutation of the LRG1 Rho-GAP gene is responsible for the hyper branching C-variant phenotype in the Quorn mycoprotein fungus Fusarium venenatum A3/5

This study investigated the genetic causes behind the appearance of colonial variants (C-variants) in Quorn mycoprotein production, which negatively impact product quality and potential yield. We identified mutations in an ortholog of LRG1 involved in fungal growth regulation, in 11 out of 12 C-variant isolates. These mutations were absent in wild-type strains and were located in the RhoGAP domain, critical for LRG1 activity. Using CRISPR/Cas9, we confirmed that introducing these mutations into the wild-type strain replicated the C-variant morphology.