Genome editing of the rutin-degrading enzyme gene FtRDE2 reduces seed bitterness in Tartary buckwheat

Tartary buckwheat (F. tataricum) is a climate-resilient pseudocereal, yet its global adoption is constrained by its bitter seeds. Here, we employed the CRISPR/Cas9 system to disrupt the rutin-degrading enzyme 2 gene (FtRDE2), which catalyses the hydrolysis of rutin to quercetin, a major contributor to bitterness. Two independent ftrde2 mutant lines showed no detectable rutinosidase activity: mutant seed extracts maintained stable rutin levels and lacked the rapid accumulation of quercetin observed in wild-type controls. Consistent with these biochemical changes, sensory evaluation showed that wild-type flour was consistently identified as more bitter than flour from either ftrde2 mutant line. These results provide direct genetic evidence that FtRDE2 is a major determinant of rutinosidase-dependent seed bitterness and demonstrate the potential of genome editing to reduce bitterness in Tartary buckwheat.