Molecular and anatomical insights in Brassica napus L., for seed shattering pathways and breeding prospects for shatter resistance

Abstract Among oilseeds crops, Brassica napus L., is of great importance globally. The economic yield and harvest efficiency are significantly limited by seed shattering, which represents a persistent agronomic constraint. In wild species, natural seed dispersal is of evolutionary importance, but it’s a serious challenge for domesticated species where seed retention is essential for yield stability. In Brassica napus L., shattering-induced pre-harvest loss can exceed up to 70% which underscores the importance of developing shatter-resistant cultivars. This review highlights the insight into genetic, hormonal, anatomical, and environmental regulation of seed shattering, with a focus on recent advancements in functional genomics and genome editing technologies. Pod dehiscence is genetically controlled by a complex regulatory network of transcription factors such as SHATTERPROOF (SHP1/SHP2), INDEHISCENT (IND), ALCATRAZ (ALC), and REPLUMLESS (RPL), which orchestrate the differentiation of the dehiscence zone. Hormonal pathways like auxin, gibberellins, and ethylene play a role in silique development, and the enzymatic degradation of the cell wall at maturity modulates these regulators. Anatomical determinants, particularly the fiber cap cell development, degree and localization of lignification, and the separation layer, also define the mechanical resistance of the silique to premature rupture. The silique wall is also different in shattering-prone and shattering-resistant genotypes. Recent advances in QTL mapping, genome-wide association studies (GWAS), and CRISPR/Cas-based gene editing have enabled precise identification and manipulation of loci for the development of shatter resistance. Seed shattering is a polygenic trait that is particularly sensitive to the influence of environmental stresses, such as drought, heat, and delayed harvesting. Despite considerable progress, integrating molecular and anatomical insights into practical breeding remains challenging. This review aims for a system-level breeding approach to develop climate-resilient, high-yielding and shatter-resistant Brassica napus L., cultivars by combining molecular genetics and agronomic optimization to ensure a sustainable production in the face of global climate challenges.