Transcriptome analysis of lipid biosynthesis during kernel development in two walnut (Juglans regia L.) varieties of ‘Xilin 3’ and ‘Xiangling’

Abstract

Abstract Background Walnut is an oilseed tree species and an ecologically important woody tree species that is rich in oil and nutrients. In light of differences in the lipid content, fatty acid composition and key genes expression patterns in different walnut varieties, the key gene regulatory networks for lipid biosynthesis in different varieties of walnuts were intensively investigated. Results The kernels of two walnut varieties, ‘Xilin 3’ (X3) and ‘Xiangling’ (XL) were sampled at 60, 90, and 120 days post-anthesis (DPA) to construct 18 cDNA libraries, and the candidate genes related to oil synthesis were identified via sequencing and expression analysis. A total of 106 differentially expressed genes associated with fatty acid biosynthesis, fatty acid elongation, unsaturated fatty acid biosynthesis, triglyceride assembly, and oil body storage were selected from the transcriptomes. Weighted gene co-expression network analysis (WGCNA), correlation analysis and quantitative validation confirmed the key role of the FAD3 (109002248) gene in lipid synthesis in different varieties. Conclusions These results provide valuable resources for future investigations and new insights into genes related to oil accumulation and lipid metabolism in walnut seed kernels. The findings will also aid future molecular studies and ongoing efforts to genetically improve walnut.

Keywords

• Walnut kernels
• Oil content
• Lipid biosynthesis
• Transcriptome sequencing
• Fatty acid
• Gene expression