Silent constraints: the hidden challenges faced in plant metabolic engineering

Metabolic engineering is embraced as a method to sustainably enhance production of valuable phytochemicals with beneficial properties. However, successful these compounds in plants not always predictable even when the pathways are fully known, frequently due lack comprehensive understanding plant metabolism whole, and interconnections between different primary, secondary, hormone metabolic networks. Here, we highlight critical hidden constraints, including substrate availability, silent metabolism, crosstalk, that impair strategies. We explore how constraints have historically been manifested attempts propose modern advancements will enable future strategies overcome impediments.