Methyl jasmonate stimulates the synthesis and accumulation of asperosaponin VI in the roots of Dipsacus asper / 药学学报

We investigated the effect of methyl jasmonate (MeJA) on the content of asperosaponin VI and the expression of genes involved in its synthesis. Dipsacus aspero seedlings were treated with MeJA at different concentrations of 50, 100, 150, 200 and 300 μmol·L-1, and leaves and roots were sampled following treatment for 1, 3 and 5 days. The content of asperosaponin VI and superoxide anion in the roots, malondialdehyde (MDA) content in leaves and superoxide dismutase were determined. The results show that 150 μmol·L-1 MeJA significantly increased the accumulation of asperosaponin VI in roots. The content of asperosaponin VI was greatest after treatment for 3 days, and was 2.16 times higher than the control. After MeJA treatment, SOD activity decreased and MDA content increased in leaves. Moreover, superoxide anion content in roots increased. The expression of squalene epoxidase (DaSE1) and geranyl diphosphate synthase (DaGPS), key enzymes in the synthesis of asperosaponin VI, were up-regulated compared with the control group. These results indicate that an optimal concentration of 150 μmol·L-1 MeJA increases the accumulation of asperosaponin VI by up-regulating the expression of key enzymes involved in the synthesis of asperosaponin VI, which facilitates resistance to adversity stress stimulated by MeJA.

Identification and expression analysis of the DaNAC transcription factor family in Dipsacus asper / 药学学报

italic>NAC transcription factor genes play an important role in regulating plant adversity stress tolerance and secondary metabolism. To explore DaNAC transcription factor participation in the synthesis of asperosaponin Ⅵ in Dipsacus asper, we analyzed the expression of DaNAC genes based on full-length transcriptome data from different tissues (root, stem, leaf, flower, seed) to provide a theoretical foundation for regulating the metabolism of D. asper. RNA-seq data was used to identify open reading frames. Bioinformatic methods were used to identify the conserved domain motifs and construct an evolutionary tree. qRT-PCR was carried out to analyze tissue-specific and adversity-stressed expression. Twenty-nine DaNAC sequences were identified, all of which contain the conserved NAM domain and conserved motif 1 and motif 2 at the N terminal. Five DaNAC genes are closely related to the NAC genes in Arabidopsis thaliana and rice that are involved in adversity stress and are clustered in the Group Ⅰ subfamily. qRT-PCR revealed that DaNAC genes are differentially expressed between tissues. The expression levels were highest in leaves, followed by roots, stems and petioles, and the lowest in flowers and seeds. Compared with normal growth conditions, the expression of four NAC genes was up-regulated by treatment with low temperature (15 ℃). The expression of three genes (34564NAC2, 33883NAC48, 6727NAC14) was up-regulated and one gene (34480NAC22) was down-regulated by 150 μmol·L-1 MeJA. The results illustrate that the expression of NAC genes is induced by adversity stress, which provides a foundation for further study on the role of NAC family members in adversity stress in D. asper.