Combined Analysis of the Metabolome and Transcriptome Sheds New Light on the Mechanisms of Seed Maturation in Amorphophallus muelleri

Abstract

Amorphophallus muelleri, a naturally occurring variant of the commercially valuable Amorphophallus species grown in Southeast Asia, stands out for its desirable traits: high konjac glucomannan (KGM) content, apomictic properties, and strong disease resistance. However, the mechanisms governing KGM maturation and biosynthesis within A. muelleri seeds remain poorly understood. Accordingly, wide-targeted metabolomics and RNA-seq were used in the present study to analyze differentially accumulated metabolites (DAMs) and differentially expressed genes (DEGs). Importantly, we sought to identify changes during A. muelleri seed maturation and KGM biosynthesis. Our findings indicated that DAMs associated with amino acids and secondary metabolites were elevated in mature seeds. Moreover, the expression of several genes was also upregulated, including those involved in flavonoid biosynthesis and plant hormone signal transduction pathways, specifically TPS5, TPS6, C4H (CYP73A12), and key genes encoding auxin and abscisic acid (ABA) synthesis (IAA10, ARF11, SAPK7). Our findings suggest that these genes play positive roles in regulating seed maturation. Additionally, seven genes encoding key enzymes involved in KGM biosynthesis were upregulated during the first two stages of seed maturation compared to the third stage of seed ripening. This indicates a potential correlation between KGM content and the expression of these genes at the post-transcript level. Finally, a strong correlation was identified between key DAMs and DEGs. Collectively, these results provide valuable insights for researchers seeking to understand the molecular mechanisms underlying A. muelleri seed maturation and KGM synthesis.