Lessons From CABBI : Advancing Vegetative Oil Production in C ₄ Crops T

ABSTRACT

The global demand for renewable liquid fuels and biobased chemicals has intensified interest in engineering high‐biomass C ₄ grasses to accumulate triacylglycerol (TAG) in vegetative tissues. Achieving this goal requires coordinated solutions across molecular biology, crop science, chemical engineering, and life cycle assessment, disciplines that rarely operate within a single research program. The Center for Advanced Bioenergy and Bioproducts Innovation (CABBI) was established to provide this integration through a Design–Build–Test–Learn (DBTL) framework applied to three C ₄ feedstocks: saccharum ( Saccharum spp. hybrids), sorghum ( Sorghum bicolor ), and miscanthus ( Miscanthus  ×  giganteus ). Through iterative DBTL cycles, CABBI has produced transgenic saccharum and sorghum lines with substantially elevated levels of vegetative TAG, with multi‐location field trials having confirmed stable trait heritability and lipid yields. We have also leveraged our integration to develop a dual system biorefinery that co‐recovers vegetative lipids with fermentable sugars at levels sufficient to achieve industrial ethanol titres. Importantly, this fully integrated cross‐disciplinary data integration model has highlighted the key constraints currently preventing TAG‐rich vegetative oil from achieving commercial viability as: (i) active lipid turnover, (ii) photosynthetic trade‐offs, (iii) spatial misexpression, and (iv) bioprocessing challenges. CABBI uses emerging technologies, including biofoundry‐enabled construct screening, precision genome editing, and machine‐learning‐assisted regulatory design, to further accelerate DBTL cycles. More broadly, this work illustrates how integrative centre‐scale research that unites diverse expertise can accelerate discovery and translation, positioning these systems to expand agricultural markets and contribute to a more secure and resilient bioeconomy.