Integrated transcriptomics and lipidomics reveal mechanisms regulating lipids formation and accumulation in oil body during walnut seed development

Area of Science:

• Plant biochemistry
• Nutritional genomics
• Molecular biology

Background:

• Lipid formation and accumulation in oil bodies (OBs) are crucial for nut quality.
• Walnut oil bodies (WOBs) are primary lipid storage sites, but their formation lacks systematic research.
• Understanding lipid dynamics in WOBs is essential for improving walnut quality.

Purpose of the Study:

• To investigate the molecular mechanisms of lipid formation and accumulation in walnut oil bodies.
• To identify key genes and metabolic pathways involved in lipid metabolism during walnut development.
• To provide genetic resources for enhancing walnut quality.

Main Methods:

• Integrated transcriptomics and lipidomics analysis of walnut kernels at multiple developmental stages (60-130 days after pollination).
• RNA sequencing to identify differentially expressed genes (DEGs) related to lipid metabolism.
• Principal component analysis and cluster analysis to group samples and DEGs.

Main Results:

• Fatty acid content in walnut kernels and WOBs showed opposite trends.
• Three distinct developmental stages were identified based on sample clustering (60-74, 88-102, 116-130 DAP).
• 228 DEGs related to lipid metabolism were identified, involved in pathways like fatty acid biosynthesis and glycerolipid metabolism. Key genes like ACC, KASII, SAD, FAD2, FAD3, and PDAT were downregulated in later stages.

Conclusions:

• The study elucidated the dynamic changes in lipids and gene expression during walnut development.
• Specific genes, particularly FAD2 and FAD3, were highlighted for their role in unsaturated fatty acid synthesis in WOBs.
• Findings provide valuable insights and genetic resources for future walnut quality improvement efforts.