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Abstract Ginseng (Panax ginseng C. A. Mey.) is an important and valuable medicinal plant species used in traditional Chinese medicine, and its metabolite ginsenoside is the primary active ingredient. The FAR1/FHY3 gene family members play critical roles in plant growth and development as well as participate in a variety of physiological processes, including plant development and signaling of hormones. Studies have indicated that methyl jasmonate treatment of ginseng adventitious roots resulted in a significant increase in the content of protopanaxadiol ginsenosides. Therefore, it is highly significant to screen the FAR1/FHY3 gene family members in ginseng and preliminarily investigate their expression patterns in response to methyl jasmonic acid signaling. In this study, we screened and identified the FAR1/FHY3 family genes in the ginseng transcriptome databases. And then, we analyzed their gene structure and phylogeny, chromosomal localization and expression patterns, and promoter cis-acting elements, and made GO functional annotations on the members of this family. After that, we treated the ginseng adventitious roots with 200 mM methyl jasmonate and investigated the trend of the expression of four genes containing the largest number of methyl jasmonate cis-acting elements at different treatment times. All four genes were able to respond to methyl jasmonate, the most significant change was in the PgFAR40 gene. This study provides data support for subsequent studies of this family member in ginseng and provides experimental reference for subsequent validation of the function of this family member under methyl jasmonic acid signaling.

Ginseng (Panax ginseng C.A. Meyer) is a perennial herb belonging to the family Araliaceae and has been used for thousands of years in East Asia as an essential traditional medicine with a wide range of pharmacological activities of its main active ingredient, ginsenosides. The AP2/ERF gene family, widely present in plants, is a class of transcription factors capable of responding to ethylene regulation that has an influential role in regulating the synthesis of major active ingredients in medicinal plants and in response to biotic and abiotic stresses, which have not been reported in Panax ginseng. In this study, the AP2/ERF gene was localized on the ginseng chromosome, and an AP2/ERF gene duplication event was also discovered in Panax ginseng. The expression of seven ERF genes and three key enzyme genes related to saponin synthesis was measured by fluorescence quantitative PCR using ethylene treatment of ginseng hairy roots, and it was observed that ethylene promoted the expression of genes related to the synthesis of ginsenosides, among which the PgERF120 gene was the most sensitive to ethylene. We analyzed the sequence features and expression patterns of the PgERF120 gene and found that the expression of the PgERF120 gene was specific in time and space. The PgERF120 gene was subsequently cloned, and plant overexpression and RNA interference vectors were constructed. Ginseng adventitious roots were transformed using the Agrobacterium tumefaciens-mediated method to obtain transgenic ginseng hairy roots, and the gene expression, ginsenoside content and malondialdehyde content in overexpression-positive hairy roots were also analyzed. This study preliminarily verified that the PgERF120 gene can be involved in the regulation of ginsenoside synthesis, which provides a theoretical basis for the study of functional genes in ginseng and a genetic resource for the subsequent use of synthetic biology methods to improve the yield of ginsenosides.