Global warming and population growth severely impact agricultural production. Agricultural adaptation should occur sustainably without affecting ecosystems and one way to address this is by understanding the processes that determine plant productivity. Recently, we showed that ectopic expression of maize cytochrome P450 PLASTOCRHON1 (PLA1) enhances biomass and grain yield by more than 10%. PLA1 produces a, yet unknown, molecule that stimulates organ growth in a non-cell -autonomous way. This organ growth stimulation only resulted in yield increase by fine-tuning the highly specific expression profile of PLA1, suggesting tight regulatory control. This project aims to identify the enzymatic reaction catalysed by PLA1 and to gain more insight in its regulation. An untargeted metabolomics analysis at different time points upon PLA1 induction will be performed to identify the substrate-product pair. The identified product will be validated by yeast feeding assays and by complementing the pla1 mutant. By means of proximity labelling, PLA1 interacting proteins will be identified and the transcriptional control of PLA1 will be assessed by targeting the regulatory elements with multiplex CRISPR. We anticipate that these findings will lead to new biostimulants and novel targets for plant breeding. Since PLA1 is part of a conserved family for which growth enhancement was shown in dicot and monocot crops, the findings of this project will be broadly applicable in agriculture.