A high-resolution transcriptomic atlas depicting nitrogen fixation and nodule development in soybean

Area of Science:

• Plant Biology
• Molecular Biology
• Genetics

Background:

• Legume root nodule development is vital for biological nitrogen fixation.
• Cellular and molecular mechanisms in determinate nodule legumes like soybean are not fully understood.

Purpose of the Study:

• To create a single-nucleus transcriptomic atlas of soybean root nodules.
• To identify cell types, regulatory genes, and pathways involved in soybean nodulation and nitrogen fixation.

Main Methods:

• Single-nucleus RNA sequencing (snRNA-seq) of soybean roots and nodules.
• RNA velocity analysis to reconstruct differentiation dynamics.
• Gene overexpression and knockout experiments (GmCRE1) to validate gene function.

Main Results:

• Annotated 17 cell types in soybean nodules, including six nodule-specific types.
• Identified cell types for ureide synthesis and reconstructed nodule differentiation dynamics.
• Validated GmbHLH93 and GmSCL1 as nodulation regulators and GmCRE1 as essential for nodule development and nitrogen fixation.

Conclusions:

• Provides a comprehensive cellular map of soybean nodulation.
• Elucidates metabolic and developmental mechanisms underlying soybean nodule formation.
• Highlights the critical role of cytokinin signaling (GmCRE1) in nitrogen fixation.