Implications of the regulatory mechanism of source-sink relationship under salt stress for enhancing stress resistance in rapeseed

Source-sink coordination is a crucial mechanism for efficient crop production. Salt stress significantly inhibits plant growth and yield formation. This review systematically examines the response mechanisms of source and sink organs under salt stress, and discusses corresponding regulatory strategies, aiming to provide a theoretical basis for developing tailored cultivation techniques for rapeseed in saline-alkali lands. Salt stress impairs the function of the source organ through multiple pathways, including the induction of osmotic stress and stomatal closure, which restricts CO2 assimilation. This leads to imbalances between metabolic accumulation and energy supply, disrupting the structure and function of photosynthetic systems, and triggering the accumulation of ROS that leads to photodamage. In response, crops adjust their source-sink balance via morphological adaptations, remodeling of sugar transporter expression and activity (e.g., SWEETs and MSTs), hormone-mediated redirection of photoassimilates to roots (e.g., abscisic acid, salicylic acid, and auxin), and activation of osmotic adjustment and ion homeostasis mechanisms, thereby alleviating salt-induced damage. Rapeseed (Brassica napus L.) exhibits strong salt tolerance and a notable capacity for Na+ accumulation in shoots, making it a promising species for simultaneous utilization and improvement of saline-alkali soils. By exploring the regulatory mechanisms of source-sink relationships under salt stress, this review proposes cultivation strategies to enhance salt tolerance in rapeseed by optimizing source-sink balance, thereby providing both theoretical and technical support for the effective utilization and reclamation of marginal lands.