Here, we aim to broaden our fundamental knowledge on lignin biosynthesis and phenolic metabolism in maize. Therefore, we will investigate the biological function of SBP1, a gene with unknown function which is tightly co-expressed with lignin biosynthetic genes in a large-scale transcriptomic database of maize. SBP1, and its close homolog SBP2, will be functionally characterized in maize by reversed genetics using CRISPR/Cas9. The SBPs are particularly highly expressed in maize roots. As the structural identity of the majority of phenolic metabolites in maize roots is currently unknown, it will be challenging to understand the anticipated metabolic response to the pathway perturbations in the sbp mutants, making it difficult to distinguish primary from secondary metabolic effects. Therefore, this project also aims at the structural characterization of a large number of phenolic metabolites in the roots of maize. To this end, state-of-the art mass spectrometry-based techniques will be combined with 13C-labeled precursor feeding and a recently developed algorithm, CSPP. This will deliver a comprehensive metabolic compendium of the maize root phenolic metabolism to the research community and speed up gene (such as the SPBs) and biosynthetic pathway discovery. This work should allow us to resolve new aspects of phenolic metabolism and lignin biosynthesis in the most grown crop world-wide, potentially opening new roads to the development of optimized feedstock for the biorefinery.