Research progress on genetic regulation of the yellow-seeded trait in Brassica Crops

Abstract

Brassica crops represent a vital global source of oilseeds and vegetables. The yellow-seeded trait has become a primary genetic improvement objective due to its close association with superior quality attributes, specifically high oil content and low fiber content. The yellow-seeded phenotype results in the inhibition of proanthocyanidin biosynthesis and deposition in the seed coat. This process is regulated by the upstream conserved MBW (TT2/TT8/TTG1) transcriptional complex, which exhibits a more complex multi-genic regulatory network influenced by maternal effects, environmental factors, and epigenetic modifications. This review provides a comprehensive comparison on the current researches across six Brassica species (B. rapa, B. oleracea, B. nigra, B. napus, B. juncea, and B. carinata), summarizes the key genes that have been functionally validated, and analyzes the metabolic and genetic basis underlying the synergistic formation of multiple traits, including yellow seeds, high oil, and low fiber. Finally, we discuss the applications and challenges in the molecular breeding strategies targeting for the yellow-seeded trait improvement, such as marker-assisted selection (MAS), CRISPR/Cas9 gene editing, and multi-omics integration. We also provide perspectives on the future potential of achieving the synergistic enhancement of quality and yield through de novo design breeding.