From wrinkled seeds to plant oil accumulation networks: the legacy of a Plant Physiology classic.

Plant seeds accumulate triacylglycerol (TAG) as a major storage reserve that supports postgermination growth and seedling establishment. Vegetable oils are also essential for human nutrition and provide renewable feedstocks for industrial and biotechnological applications. In 1998, Focks and Benning published a landmark study in Plant Physiology describing the Arabidopsis WRINKLED1 mutants (wri1), which display a distinctive wrinkled seed phenotype and a dramatic reduction in seed oil accumulation. The conceptual importance of this discovery was not simply the identification of a low-oil mutant, but the demonstration that seed oil accumulation depends on developmental control of carbon flux from carbohydrates into fatty acid precursors. Cloning of the Arabidopsis WRI1 (AtWRI1) gene in 2004 transformed this physiological phenotype into a molecular framework by identifying WRI1 as a member of the APETALA2 (AP2) family of transcription factors that activates late glycolytic and fatty acid biosynthetic genes. Subsequent work uncovered the AW-box cis-element, upstream seed-maturation regulators, WRI1-interacting partners, post-transcriptional and post-translational modification mechanisms controlling WRI1 stability and activity, and the structural basis of WRI1-DNA recognition. These discoveries established WRI1 as a central regulatory node linking seed development, carbohydrate metabolism, and seed oil accumulation. More recent studies have broadened WRI1 biology beyond canonical seed oil biosynthesis to include non-seed oil-storing tissues, hormone and nutrient-associated processes, environmental responses, and structure-guided crop engineering. Here, we revisit the original Plant Physiology classic and trace how one mutant phenotype reshaped modern understanding of plant carbon partitioning, transcriptional regulation, and metabolic engineering.