Shade stress triggers ethylene biosynthesis to accelerate soybean senescence and impede nitrogen remobilization

• Published in: Plant physiology and biochemistry 2024-05, Vol.210, p.108658-108658, Article 108658
• Main Authors: Deng, Juncai, Huang, Xiangqing, Chen, Jianhua, Vanholme, Bartel, Guo, Jinya, He, Yuanyuan, Qin, Wenting, Zhang, Jing, Yang, Wenyu, Liu, Jiang
• Format: Article
• Language: English
• Subjects: Ethylene; Leaf senescence; Nitrogen remobilization; Shade; Soybean
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2024.108658

In gramineae-soybean intercropping systems, shade stress caused by taller plants impacts soybean growth specifically during the reproductive stage. However, the effects of shade stress on soybean senescence remain largely unexplored. In this research, we applied artificial shade treatments with intensities of 75% (S75) and 50% (S50) to soybean plants at the onset of flowering to simulate the shade stress experienced by soybeans in the traditional and optimized maize-soybean intercropping systems, respectively. Compared to the normal light control, both shade treatments led to a rapid decline in the dry matter content of soybean vegetative organs and accelerated their abscission. Moreover, shade treatments triggered the degradation of chlorophyll and soluble proteins in leaves and increased the expression of genes associated with leaf senescence. Metabolic profiling further revealed that ethylene biosynthesis and signal transduction were induced by shade treatment. In addition, the examination of nitrogen content demonstrated that shade treatments impeded the remobilization of nitrogen in vegetative tissues, consequently reducing the seed nitrogen harvest. It's worth noting that these negative effects were less pronounced under the S50 treatment compared to the S75 treatment. Taken together, this research demonstrates that shade stress during the reproductive stage accelerates soybean senescence and impedes nitrogen remobilization, while optimizing the field layout to improve soybean growth light conditions could mitigate these challenges in the maize-soybean intercropping system. •Shade stress leads to premature senescence in soybean plants.•Ethylene biosynthesis and signal transduction are induced to regulate soybean plant senescence.•Shade stress retains nitrogen in soybean vegetative organs and impedes the remobilization of nitrogen from these organs.•These negative impacts can be mitigated by reducing the intensity of shade stress through field layout optimization.