Haplotype-phased genome unveils the butylphthalide biosynthesis and homoploid hybrid origin of Ligusticum chuanxiong.

Butylphthalide is one of the first-line drugs for ischemic stroke therapy, while no biosynthetic enzyme for butylphthalide has been reported. Here, we present a haplotype-resolved genome of Ligusticum chuanxiong, a long-cultivated and phthalide-rich medicinal plant in Apiaceae. On the basis of comprehensive screening, four Fe(II)- and 2-oxoglutarate-dependent dioxygenases and two CYPs were mined and further biochemically verified as phthalide C-4/C-5 desaturases (P4,5Ds) that effectively promoted the forming of (S)-3-n-butylphthalide and butylidenephthalide. The substrate promiscuity and functional redundancy featured for P4,5Ds may contribute to the high phthalide diversity in L. chuanxiong. Notably, comparative genomic evidence supported L. chuanxiong as a homoploid hybrid with Ligusticum sinense as a potential parent. The two haplotypes demonstrated exceptional structure variance and diverged around 3.42 million years ago. Our study is an icebreaker for the dissection of phthalide biosynthetic pathway and reveals the hybrid origin of L. chuanxiong, which will facilitate the metabolic engineering for (S)-3-n-butylphthalide production and breeding for L. chuanxiong.

Sequencing and Comparative Analysis of the Chloroplast Genome of Angelica polymorpha and the Development of a Novel Indel Marker for Species Identification.

The genus Angelica (Apiaceae) comprises valuable herbal medicines. In this study, we determined the complete chloroplast (CP) genome sequence of A. polymorpha and compared it with that of Ligusticum officinale (GenBank accession no. NC039760). The CP genomes of A. polymorpha and L. officinale were 148,430 and 147,127 bp in length, respectively, with 37.6% GC content. Both CP genomes harbored 113 unique functional genes, including 79 protein-coding, four rRNA, and 30 tRNA genes. Comparative analysis of the two CP genomes revealed conserved genome structure, gene content, and gene order. However, highly variable regions, sufficient to distinguish between A. polymorpha and L. officinale, were identified in hypothetical chloroplast open reading frame1 (ycf1) and ycf2 genic regions. Nucleotide diversity (Pi) analysis indicated that ycf4⁻chloroplast envelope membrane protein (cemA) intergenic region was highly variable between the two species. Phylogenetic analysis revealed that A. polymorpha and L. officinale were well clustered at family Apiaceae. The ycf4-cemA intergenic region in A. polymorpha carried a 418 bp deletion compared with L. officinale. This region was used for the development of a novel indel marker, LYCE, which successfully discriminated between A. polymorpha and L. officinale accessions. Our results provide important taxonomic and phylogenetic information on herbal medicines and facilitate their authentication using the indel marker.

Identification of Species in the Aromatic Spice Family Apiaceae Using DNA Mini-barcodes.

The species of the aromatic plant family Apiaceae are mainly used as spices and foods, but the family also includes medicinal and some poisonous plant species. Due to the similar chemical compounds or aroma and morphology, the poisonous species are often mistaken for the edible aromatic species. It is therefore imperative to correctly identify the species present at the initial raw stage samples to ensure product safety and efficacy. At the molecular level, plant species can be identified using DNA loci either from nuclear or plastid genome with easily available universal oligonucleotides, a technique called DNA barcoding. However, this is possible when single-species plant material is present but may not work on a mixture of plants species. Another disadvantage is that using universal oligonucleotides is of limited help, especially if the adulterating material is present in low quantities. On the other hand, if using the species-specific oligonucleotides, only single specific adulterating plant material could be detected and, consequently, the unexpected adulterants may go undetected. Therefore, in the current work, four degenerated oligonucleotides from ITS1 and ITS2 regions of the nuclear genome were designed that can bind to a variety of Apiaceae genera only and not to other genera belonging to different plant families. These family-specific oligonucleotides were able to amplify a diagnostic PCR product from 16 Apiaceae species that, upon sequencing, revealed the identity of the plant it was derived from. The size of these products is around 140 bp for ITS1 and approximately 80 bp for the ITS2 region. The size range of the amplified products falls in the category of a desired mini-barcode size to be used for damaged/fragmented DNA and next generation sequencing.

[Analysis of endophytic fungi community of Ligusticum chuanxiong using PCR-DGGE].

OBJECTIVE: To research the diversity of endophytic fungal communities among Ligusticum chuanxiong growing at 5 areas in Sichuan province, and illuminate the developing mechanism of geoherbs from the microecological perspective. METHOD: The PCR-DGGE and DNA sequencing techniques were used to analyze the endophytic fungi community of L. chuanxiong. RESULT: The community of endophytic fungi present difference among different growing areas. Though minor difference were found among individuals at the same area, similarity among individuals from the same growing areas were higher significantly than those from different growing areas. Compared with the other 4 growing areas, L. chuanxiong from Shiyang town, Dujiangyan city had more abundant endophytic fungi and low similarity to others, and which probably had special types of fungi. CONCLUSION: The abundant and stable endophytic fungal community is an important factor for the development of geoherb L. chuanxiong at Shiyang town, Dujiangyan city.

Authentication of the oriental medicinal plant Ligusticum tenuissimum (Nakai) Kitagawa (Korean Go-Bon) by multiplex PCR.

The oriental medicinal plant Ligusticum tenuissimum (Korean name, Go-Bon) is widely used in Korea and China. L. tenuissimum (Go-Bon) has been employed in the treatment of headache and common cold, and as a fever remedy. The internal transcribed spacer (ITS) region was sequenced from thirty-four Go-Bon samples collected from botanical gardens and markets in Korea and China to identify and authenticate L. tenuissimum. Based on the ITS sequences, the thirty-four Go-Bon samples were classified into three groups: L. tenuissimum (Korean Go-Bon), L. jeholense (Chinese Go-Bon), and unknown Chinese Ligusticum species. Three specific primers were designed to identify the three groups of Ligusticum species using multiplex PCR. The established multiplex-PCR was proved to be effective for the differentiation of L. tenuissimum in commercial plant materials.

Molecular identification of "Chuanxiong" by nucleotide sequence and multiplex single base extension analysis on chloroplast trnK gene.

Chloroplast trnK gene sequences of Cnidium officinale and Ligusticum chuanxiong were determined to establish an effective method for identifying Japanese Senkyu and Chinese Chuanxiong, the two which have the same drug name in Chinese characters, similar external feature, but different botanical origins. Three sites of nucleotide differences were found between these 2 species at positions 767,924 and 964 from upstream in trnK gene sequence, allowing molecular identification of the two plants and crude drugs. Further, three kinds of specific primers of 14 mer, 23 mer and 30 mer long were designed to detect these 3 sites of marker nucleotides. By using multiplex single base extension (MSBE) analysis with the 3 specific primers, C. officinale and L. chuanxiong could be distinguished clearly by the electrophoretograms, where 3 peaks with different color of ddTMP, ddCMP and ddTMP were observed in case of C. officinale and those of ddGMP, ddAMP and ddGMP in L. chuanxiong. Moreover, trnK gene sequence of "Dongxiong," a kind of Chuanxiong cultivated in Northeast China, suggested that its botanical origin was C. officinale.