Phenylpropanoid accumulation and gene expression in Agastache rugosa leaves and flowers stages

Abstract

Agastache rugosa is a medicinal plant that belongs to the Lamiaceae family of plants and is most commonly found in Korea. It contains various phenolic compounds with antifungal and anti-human immunodeficiency virus properties. This study aimed to investigate changes in the phenylpropanoid levels and the transcript levels of phenylpropanoid biosynthetic genes in the leaves, flowers, and roots of A. rugosa at different developmental stages. After 39 days of growth, plants were collected at designated time points. The harvested samples were subsequently subjected to an analysis. High-performance liquid chromatography (HPLC) was employed to assess the chemical composition, while quantitative real-time polymerase chain reaction (qRT-PCR) was utilized to evaluate the gene expression levels. The concentration of rosmarinic acid (RA) increased steadily as the leaves and flowers developed, whereas the concentrations of tilianin and acacetin decreased. Among the different developmental stages of the leaves, flowers and root, L5 (leaf size of 9 cm) showed the highest levels of RA (15.5 mg·g-1), while L1 showed the highest levels of tilianin and acacetin (4.9 and 1.7 mg·g-1, respectively). F4 (full flowering) showed the highest levels of RA (6.5 mg·g-1), tilianin (6.6 mg·g-1), acacetin (6.8 mg·g-1). The roots of A. rugosa contained only RA (12.1 mg·g-1). A. rugosa leaves in the L1 phase exhibited significant expression levels of genes related to the phenylpropanoid biosynthesis of Tilianin, including ArPAL, ArC4H, ArCHS, and ArCHI. In this study, we identified and quantified health-promoting compounds in the leaves and flowers of Agastache rugosa. Our research findings endorse the medicinal potential of A. rugosa while also highlighting specific areas for enhancing the production of tilianin, acacetin, and rosmarinic acid within this plant. ⓒ 2024 Korean Society for Horticultural Science.