The immobilization of P. canescens spores (Figure 2b) in CAG beads was prepared according to the method described by Yao et al. (2014). AMHRCs (Figure 2d) were initiated by culturing a high-productive hairy root line (AMHRL VI) (Figure 2c) under the optimal conditions as reported by Jiao et al. (2015). AG standards including AG I, AG II, IAG II and AG IV were purchased from Weikeqi Biological Technology Co. Ltd. (Sichuan province, China). MiniBEST Plant RNA Extraction Kit, PrimeScript? RT reagent Kit and SYBR Premix Ex Taq? II Kit were provided by TaKaRa (Dalian, China). Other reagents of either analytical or optical grades were purchased from Beijing Chemical Reagents Co. (Beijing, China). Ultrapure water was prepared from a Milli-Q system at 18.3 M resistance (Millipore, Bedford, MA).

Astragaloside and isoavonoid standards, including astragaloside I (AG I), astragaloside II (AG II), isoastragaloside II (IAG

II), astragaloside III (AG III), astragaloside IV (AG IV), cycloastragenol (CY), calycosin-7-O-b-D-glucoside (CAG), ononin

(ON), astraisoavan-7-O-b-D-glucoside (ASG), calycosin (CA) and

formononetin (FO), were purchased from Weikeqi Biological

Technology Co. Ltd. (Sichuan province, China). Other reagents

of either analytical or optical grade were obtained from Beijing

Chemical Reagents Co. (Beijing, China).

The TWMM was provided by Beijing HanDian Pharmaceutical Co., Ltd. (Beijing, China). Chlorogenic acid, linarin, luteolin, jaspolyside, tolbutamide, stachydrine, magnoflorine, calycosin-7-O-β-d-glucoside, stepharanine, jatrorrhizine, epiberberine, columbamine, ononin, berberine, palmatine, berberrubine, calycosin, formononetin, 2α-hydroxyoleanic acid, hydroxytyrosol, salidroside, luteolin-7-O-glucoside, verbascoside, specnuezhenide, oleuropein, physcion, oleonuezhenide, astragaloside IV, astragaloside II, isoastragaloside II, astragaloside I, luteolin, formononetin, and tolbutamide (purity ≥ 98%) were purchased from Shanghai Yuanye Pharmaceutical Technology Co., Ltd and Sichuan Weikeqi Pharmaceutical Technology Co., Ltd. Acetonitrile and formic acid both in HPLC grade were obtained from Fisher Scientific (Fair Lawn, NJ, USA). Ultrapure water was prepared using a Milli-Q water purification system (Millipore, Bredford, MA, USA). Other reagents were all analytical grade.

AG standards including AG I, AG II, IAG II, AG III, AG IV and CY were purchased from Weikeqi Biological Technology Co., Ltd. (Sichuan province, China). UV-A, UV-B and UV-C lamps (40 W) were bought from Beijing Institute of Electric Light Source (Beijing, China).

Mature seeds of A. membranaceus were generously provided by Heilongjiang University of Chinese Medicine. AG standards including AG I, AG II, IAG II, AG III, AG IV and CY were purchased from Weikeqi Biological Technology Co. Ltd. (Sichuan province, China). Other reagents either of analytical or optical grades were obtained from Beijing Chemical Reagents Co. (Beijing, China).

sucrose and 1 g/L casein hydrolyzate but without NH4NO3, at 25 ± 1 °C in the dark. AG standards including astragaloside I (AG I), astragaloside II (AG II), isoastragaloside II (IAG II), astragaloside III (AG III), astragaloside IV (AG IV) and cycloastragenol (CY) were purchased from Weikeqi Biological Technology Co., Ltd. (Sichuan province, China). Elicitors (MJ, SA and ASA) were obtained from Sigma–Aldrich Co.

Glycyrrhetinic acid was purchased from Shanghai Yuanye Biological Technology Co. Astragaloside I, astragaloside II, astragaloside IV, calycosin?7?O?β?d?glucoside, ononin, formononetin and liquiritin were obtained from Sichuan Weikeqi Biotechnology Co. The purity of each standard substance was larger than 98%. The roots of Astragalus propinquus Schischkin were collected in Longxi County, Gansu Province (lot: 160901) and authenticated by Prof. Chen Jianwei in the field. The raw materials of AP