Transcriptome-Based Analysis of Mitochondrial Influence on Key Agronomic Traits and Nutritional Components in Auricularia heimuer

Mitochondria play a pivotal role in fungal growth, development, and metabolic regulation, yet their significance has often been overlooked in traditional breeding programs. Auricularia heimuer, the second most widely cultivated edible fungus in China, has attracted increasing attention due to its nutritional and health-promoting properties, underscoring the urgent need for the development of functional cultivars and the elucidation of mitochondrial regulatory mechanisms. In this study, we constructed isonuclear alloplasmic strains with identical nuclear genotypes but distinct mitochondrial backgrounds. Comparative analyses of mycelial growth, fruiting body morphology, and nutritional composition were conducted, alongside transcriptomic profiling. The results showed no significant morphological differences on sawdust-based medium; however, on PDA medium, the strains exhibited notable differences in growth rate, melanin content, β-glucan levels, iron ion concentration, and amino acid content. Transcriptomic analysis identified 3385 differentially expressed genes (DEGs), which were enriched in pathways related to lysine biosynthesis, purine metabolism, DNA replication, and repair. Key DEGs involved in lysine biosynthesis were found to encode aminoadipate reductase (AAR) and saccharine dehydrogenase (SDH), with AAR localized in the cytoplasm and potentially regulating lysine synthesis through its enzymatic activity. This study highlights the critical influence of mitochondrial genes on the metabolic composition and transcriptional landscape of A. heimuer, providing a theoretical foundation for genetic improvement and the development of functional fungal cultivars.