Combined analysis of the metabolome and transcriptome reveals candidate genes involved in lipid metabolism in Heuchera micrantha Douglas ex Lindl.

Abstract

Heuchera micrantha is widely used as a ornamental plant due to its strong environmental adaptability. The lipid metabolites in its leaves have obvious effects on biotic and abiotic stresses. However, the molecular mechanisms underlying lipid metabolism remain poorly understood. A total of 125 lipid metabolites were obtained from the four varieties, of which 109 were common to all four varieties, while very few (a maximum of four) were unique to a single variety. All these lipid metabolites could be classified into one of the following five classes: glycerol ester, phosphatidylcholine, lysophosphatidylcholine, lysophosphatidylethanolamine, and free fatty acids. Most could be classified as free fatty acids. Principal component analysis separated the four varieties into three groups. A total of 79 differential lipid metabolites were identified, with γ-linolenic acid, α-linolenic acid, 12-hydroxydodecanoic acid, lysoPC 18:3 (2n isomer), lysoPE 16:0 (2n isomer), and lysoPE 16:0 being the main differential lipid metabolites among the four varieties. Transcriptome data from the four varieties revealed a total of 1733 differentially expressed genes (DEGs), which could be annotated into 15 KEGG pathways related to lipid metabolism. K-means clustering analysis of differential lipid metabolites and DEGs identified a total of 12 key candidate genes: 1 AOC, 1 new gene, 1 PYCT, 1 DPP, 1 KASII, 1 LCAT, 1 AKR, 1 CYP94A5, 1 GLB, 2 LACS, and 1 ACOX3. The AOC gene plays an important role in the synthesis of α-linolenic acid and γ-linolenic acid. KASII and LACS mainly control the levels of free fatty acids, while AKR and DPP affect the glycerol ester content. Taken together, these results provide insight into the molecular mechanism of lipid metabolism and provide valuable information about the formation of lipid metabolites in H. micrantha.