The complete genome assembly of Astragalus membranaceus: enabling more accurate genetic research.

Background: Astragalus membranaceus (Fisch.) Bunge is a globally significant medicinal plant renowned for its potent immunomodulatory and antioxidant properties. However, the existing reference genome for this species remains incomplete, characterized by fragmented assemblies and the absence of centromeric and telomeric regions, thereby limiting comprehensive exploration of the genetic mechanisms underlying its key traits.

Findings: We hereby present the first complete genome assembly for A. membranaceus (Fisch.) Bge "AM-T2T," achieved through the integration of PacBio HiFi, ultra-long Oxford Nanopore Technologies, and Hi-C sequencing. The assembly achieved a total size of 1.39 Gb with an N50 of 180.45 Mb. The genome exhibits remarkable completeness (99.63% BUSCO completeness; long terminal repeat assembly index of 22.67) and high accuracy (quality value of 57.51; Genome Continuity Inspector score of 36.23). It features annotations of 64.22% repetitive sequences, 16 telomeres, 8 centromeres, 32,600 high-confident genes, 248 cytochrome P450 monooxygenases (CYP450s), and 163 uridine diphosphate glycosyltransferases. Notably, 158.58 Mb of previously unassembled regions were resolved, harboring 4 CYP450s. Additionally, 2,267 unique genes and 20,652 conserved genes were identified within the AM-T2T genome. Comparative analysis with Astragalus mongholicus assembly revealed 1,413 structural variations.

Conclusions: This complete genome assembly of A. membranaceus represents a significant advancement in the genomic characterization of A. membranaceus, providing a robust resource that will bolster genetic research, breeding programs, and medicinal applications.