Integrated Analysis of Metabolome and Transcriptome Provides New Insights into the Genetic Basis Underlying the Regulation of α-Linolenic Acid Biosynthesis in Perilla frutescens Seeds

Abstract

Perilla (Perilla frutescens) is an important oil-bearing crop rich in α-linolenic acid (ALA), and seed oil quality varies greatly among different germplasms. However, the molecular and metabolic mechanisms underlying genotypic differences in ALA accumulation remain unclear. In this study, four Perilla varieties with distinct seed phenotypic traits were used to investigate the variations in seed quality, metabolome, and transcriptome. Significant genotypic differences were observed in seed color, thousand-grain weight, and oil content. QO8 showed the highest seed oil content, while QS5 and QO10 exhibited relatively lower oil accumulation levels. Metabolome analysis revealed that lipid metabolism was the dominant metabolic category in Perilla seeds. Multiple differentially accumulated metabolites (DAMs), including ALA, stearic acid, traumatic acid, and 10-OPDA, displayed genotype-specific accumulation patterns. KEGG enrichment demonstrated that α-linolenic acid metabolism and unsaturated fatty acid biosynthesis were the most significantly divergent pathways among different Perilla germplasms. Transcriptome analysis identified numerous differentially expressed genes (DEGs) involved in fatty acid and ALA biosynthesis, such as FAD2, LOX, AOS, AOC, OPR, KAT, ECH, and ACOX. Integrated transcriptome and metabolome analysis further confirmed that the differential expression of structural genes altered the metabolic flux of the ALA and downstream jasmonic acid pathway, resulting in varied accumulation of core lipid intermediates. In addition, WRKY and MYB transcription factors were identified as key upstream regulators that positively or negatively modulated ALA metabolic homeostasis. This study systematically clarified the phenotypic, metabolic, and transcriptional differences in seeds of different Perilla varieties and revealed the core regulatory network of ALA biosynthesis. These findings provide valuable candidate genes and a theoretical foundation for elucidating the molecular mechanism of high ALA accumulation and quality improvement in Perilla seeds.