Modulation of Lignin and Anthocyanin Homeostasis by GTP Cyclohydrolase1 in Maize

Maize is an essential biomass resource with substantial potential for diverse agricultural applications. Anthocyanins are powerful antioxidants, which play a critical role in protecting human health by neutralizing free radicals and reducing oxidative stress. Notably, anthocyanin and lignin biosynthesis pathways compete for shared precursors in plants, and higher lignin content can affect the digestibility of silage. In this study, we identified the candidate gene ZmGCH1 for the bm6 mutant through fine-mapping, and mutations in this gene divert more of the shared precursors from the lignin biosynthetic pathway toward anthocyanin synthesis. Further investigation revealed that ZmGCH1 interacts with ZmPEBP15 to jointly limit the activity of chalcone synthase, thereby stabilizing the distribution of precursors shared between lignin and anthocyanin synthesis. Additionally, we introduced bm6 into two maize varieties, Zhengdan958 and Xianyu335, and confirmed through an in vitro rumen digestion experiment with cattle that bm6 significantly enhances feed digestibility.