• 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.

Poly-γ-glutamic acid (γ-PGA) is a valuable biopolymer with diverse industrial applications, produced naturally by several Bacillus species. The dairy environment is an under-explored niche for identifying efficient, food-grade γ-PGA producers. In this study, four legacy dairy-derived Bacillus licheniformis strains: DPC3803, DPC6338, DPC6339, and DPC6340, producing high γ-PGA titres were examined using whole genome sequencing (WGS) and comparative genomic analysis to evaluate their suitability for future industrial applications. The genomes ranged from 4.19 to 4.29 Mb with an average GC content of 45.8–46.2%. Pangenome analysis of the four strains, together with 51 publicly available B. licheniformis genomes, identified 12,415 gene clusters, of which 18.9% and 81.1% were core and accessory genes respectively. Average nucleotide identity (ANI) analysis demonstrated >99% sequence identity among all 55 B. licheniformis genomes, despite their isolation from diverse environments, indicating strong genomic conservation within the species. Experimental validation confirmed γ-PGA production by all four strains, with maximum titres (g/L) of 43.27 ± 1.49, 59.54 ± 4.33, 27.93 ± 1.87, and 47.74 ± 0.19 for DPC3803, DPC6338, DPC6339, and DPC6340, respectively. Genomic screening revealed multiple γ-PGA metabolism and CAZyme-encoding genes, as well as unique secondary metabolite clusters with potential antimicrobial activity. Although no plasmids or virulence factors were detected, twenty-one prophages were identified, sharing no significant homology with known cultivated phages, and a single β-lactamase gene suggested intrinsic resistance to β-lactams. These findings highlight the genomic and functional potential of these dairy-derived B. licheniformis as efficient, food-grade candidates for industrial γ-PGA production.