De novo transcriptome analysis of somatic embryogenesis induced by plant hormones combined with adenosine 5-monophosphate and nicotinamide adenine dinucleotide molecules in Aspilia africana (Pers.) C.D.Adams

• First molecular study of Aspilia africana by denovo transcriptome sequencing. • Insights into somatic embryogenesis induced by plant hormones combined with other mitogenic molecules. • Somatic embryogenesis candidate genes including SERK2, ERF12, and LEA14-A were up-regulated. • Observed similar mechanisms to that of somatic embryogenesis induced by plant hormones alone. Aspilia africana (Pers.) C.D.Adams is an important medicinal plant in Africa. In a previous study, we induced direct somatic embryogenesis (SE) from its leaf explants, by combining plant hormones with adenosine 5′-monophosphate (AMP) and nicotinamide adenine dinucleotide (NAD). SE is a valuable biotechnological tool with various applications such as synthetic seed production, and understanding molecular events that induce SE is vital for its effective manipulation and improvement. Therefore, this study aimed to elucidate the molecular basis of SE induced by a combination of plant hormones and other mitogenic molecules (AMP and NAD) in A. africana . Using NovaSeq 6000 (Illumina, Inc., USA) technology, we conducted denovo transcriptome sequencing of leaf tissues representing three distinct SE developmental stages: non-embryonic leaf (NEL), globular embryo formed leaf (GEL), and cotyledonary embryo formed leaf (CEL). A total of 8669 genes were differentially expressed in the three samples, and transcripts encoding plant hormone signalling components including auxin and cytokinin were markedly enriched. SE candidate genes such as SERK2, ERF12, ERF2, and LEA14-A were up-regulated in embryogenic tissues. Additionally, qRT-PCR analysis confirmed the expression levels of some selected SE related genes. For the first time, this study reports a de novo transcriptome assembly and gene expression analysis during SE induction in A. africana . The work also provides insights into SE induced by a combination of plant hormones with other mitogenic molecules, and findings suggest that the mechanism of SE induction in this case may be the same or similar to that induced by only plant hormones. Overall, this study offers beneficial resources for future molecular research on A. africana , and may be a key resource platform for future functional research in plant embryogenesis.