Benefits of Pseudomonas poae s61 on Astragalus mongholicus growth and bioactive compound accumulation under drought stress

ABSTRACT The aim of this study was to explore the beneficial effects of endophytic Pseudomonas poae strain S61 on medicinal plant Astragalus mongholicus. Growth and production of indoleacetic acid (IAA) of the strain was firstly characterized under stress conditions, demonstrating that the strain performance was more robust in the medium containing 20% PEG6000. Beneficial effects of the strain on host seedlings were then investigated by pouring 20% PEG6000 for 3 weeks to mimic drought stress. Among growth parameters, root biomass and root-shoot ratio were significantly enhanced by the combination of 20% PEG6000 with the strain inoculation while the individual trial had no effect. The combination trial also increased calycosin-7-O-glucoside and ononin accumulations in the roots, suggesting that the strain executed beneficial effects on A. mongholicus only when it grew under drought stress. Using MDA as lipid peroxidation parameter, our result indicated that leaf lipid peroxidation should be involved in the process.


Introduction
In Chinese medicine, roots of Astragalus mongholicus are authorized as Astragali Radix (ie Huangqi in Chinese) and have been used as tonic and diuretic for thousands of years. At present, it is widely used in clinical practice for treating nephritis, diabetes and cancer, which is contributed to bioactive polysaccharides, saponins, flavonoids and amino acids contained in the herb (Auyeung et al. 2016). At present, A. mongholicus plants used for medical practice are mainly distributed in arid and semiarid regions of China such as Shanxi, Shaanxi, Gansu, Inner Mongolia, Jilin and Heilongjiang provinces. Historically, the crude herb in Hunyuan County of Shanxi province is well accepted as geo-authentic.
Due to over-exploitation of the wild resource and increasing demand for healthy products, the geo-authentic wild A. mongholicus plant has become endangered and a large proportion of commercial herb in the market is supplied by conventionally cultivated plants. Inevitably, the application of the conventional cultivation confronts a series of problems including the undesired quality of the raw herb. It is urgent to understand the relationship between abiotic and biotic factors and the quality formation of the herb, which will be useful for solving the above problems. Using a combined chemometric analysis of chemical components with genetic variation, climatic and edaphic traits, an updated work demonstrates that the quality formation of the herb is tightly associated with the geographic and climate factors (Li et al. 2017). As plant microbiota is differentiated from the surrounding soil biome that is determined by edaphic and climate factors (Bulgarelli et al. 2013), it is desirable to explore its potentials associated with A. mongholicus growth and bioactive compound accumulations.
Endophytes are microbes that can be found living inside plant tissues, where they can live on the metabolites produced by the host (ie commensal endophytes) or execute beneficial effects to the plant, such as protection against invading pathogens and herbivores, and plant growth-promotion (Pańka et al. 2013;Santhanam et al. 2015;Li et al. 2016). The mechanisms by which beneficial microbes support plant growth and health include increasing nutrient availability, improving soil structure, inducing plant defense mechanisms, producing antibiotics, outcompeting pathogens and providing growthstimulating substances or enzymes. Their promotion on bioactive compound biosynthesis and accumulation has been explored in a few medical plants such as Salvia miltiorrhiza, Atractylodes lancea and Artemisia annua (Li et al. 2012;Ming et al. 2013;Yuan et al. 2016;Zhou et al. 2016). For A. mongholicus plants in Hunyuan, our previous work has revealed that their root microbiota was more complex and unique when compared to the specimens of the other production regions (Sun et al. 2017a). However, their potentials for improving the quality and production of the herb are underestimated.
On the other hand, some latent pathogens might inhabit inside the plant tissue and constitute the third group of endophytic consortia (Scortichini and Loreti 2007). Generally, they can have neutral or detrimental effects to the host under normal growth conditions, whereas they can be beneficial under more extreme conditions. This means that some members of endophytic consortia have dual roles as potential pathogens and as beneficial endophytes. The balance between these two states depends not only on the host genotype, but on locally occurring abiotic stress factors (Bacon et al. 2008). Although it is well accepted that increasing plant stress tolerance is associated with host antioxidative defense system (Devi et al. 2017;Hashem et al. 2018), straindependent regulation has also been indicated (Tamosiune et al. 2018). Hence, it is crucial to explore benefits of endophytic members on their hosts grown under stressed conditions and to understand underlying antioxidative defense mechanism.
The species Pseudomonas poae was first reported on a strain isolated from the phyllosphere of Poa spp. (Behrendt et al. 2003). Endophytic P. poae JA01 show potential activities as biocontrol agents against phytopathogenic fungi in Ginseng (Cho et al. 2007). Its antagonistic effect on soilborne pathogen Rhizoctonia solani was then reported based on the work of P. poae strain RE*1-1-14 that was isolated from the internal part of sugar beet root (Zachow et al. 2008). Enhanced phosphate solubilization was detected when the strain was cultured at lower temperature (Vyas et al. 2009). Its plant growth promotion has been reported in sugar beet and lettuce plants (Zachow et al. 2010). A novel lipopeptide poaeamide has been identified and is responsible for pathogen suppression and root colonization (Zachow et al. 2015). In addition, the species can be used as promising candidates for bioaugmentation (Rinland and Gomez 2015) and a bacterial consortium including P. poae could degrade cooking oil in wastewater (Nzila et al. 2017). However, no reports are available on the performance of P. poae under other stress conditions generated by environmental factors in medical plants.
The goal of the present work was to explore potentials of endophytic P. poae strain S61 on quality formation of A. mongholicus plant host. Firstly, in intro production of indoleacetic acid (IAA) was investigated in liquid medium containing varible levels of NaCl and PEG6000 or with different pH value. Based on the results, its beneficial effects on A. mongholicus plant growth and bioactive compound accumulation were explored as well as underlying antioxidative mechanism by pot experiment under drought stress. In our view, this was the first report on its limited beneficial effects in medical plants, which will be useful for understanding the quality formation of medical plants resulted from the interaction between host plant and endophytic bacteria.

Materials and methods
Isolation and characterization of P. poae strain S61 The strain S61 was isolated from the internal part of A. mongholicus plant roots in Hunyuan, Shanxi by the method of . It contains ACC deaminase, as indicated by complete genome sequencing of P. poae RE*1-1-14 (Müller et al. 2013). After successively cultured in Luria-Bertani (LB) solid medium for five times, its colony forming unit appeared in light yellow, suggesting that it can stably produce pigment. In addition, the strain can synthesize indoleacetic acid (IAA) when cultured in LB liquid medium containing 1% tryptophan (Trp). The strain was maintained at −80°C in LB liquid medium supplemented with 20% (v/v) glycerol. At present, the strain has been stored at China General Microbiological Culture Collection Center (CGMCC No. 14946) (Beijing, China).
Stress tolerance and the production of IAA Stress factors include salinity, desiccation and acidity. For salinity trial, 1%, 3%, 5% and 7% NaCl were respectively added into the LB liquid medium before inoculation. The normal medium was used as control. For acidity trial, the LB medium was adjusted to pH 5.0, 7.0 and 9.0 using HCl/NaOH. The tolerance of the strain to desiccation was examined in LB medium amended with 0%, 5%, 10%, 15% and 20% PEG6000. In addition, the medium was supplemented with 1% Trp and triplicates were applied for each trial. The trials were performed in 15 × 150 mm tubes containing 2 ml liquid medium and 1‰ initial inoculum was applied. The tubes were incubated at 28°C and shaked at 180 rpm until early logarithmic phase of the normal control. The absorbance at the wavelength 600 nm was measured using a spectrophotometer (Effendorf, Germany) to evaluate the strain growth performance. Afterwards, dynamic growth and production of IAA were quantified under 7% NaCl, 20% PEG6000 and pH 5.0. The quantification of IAA was performed by the spectrophotometric method described by Beffa et al. (1990).

Inoculum preparation and seed treatment
To prepare endophytic inoculant, after grown overnight the liquid culture of the strain S61 was centrifuged at 12,000 rpm for 10 min, then the pellets were washed with 300 mM MgCl 2 for two times, finally resuspended in 300 mM MgCl 2 and adjusted to an OD 600 of 1.0 for immediately use.
Seeds of A. mongholicus were presented by Shanxi Beiyue God Qi (Hunyuan, Shanxi). In the lab, the seeds were firstly surface sterilized as follows: washed in 75% ethanol for 1 min with shaking and rinsed with distilled and autoclaved water three times; then sinked in 5% sodium hypochlorite for 20 min, followed by rinsing with distilled and autoclaved water 5∼6 times. The last wash was plated onto the LB solid medium and there should be no growth of microbes after cultured at 28°C for 72 h. The sterilized seeds were then incubated at 50°C in a water bath (HHS Type, Tianjinshi Huabei, Tianjin, China) for 10 min. After cooling down to room temperature, the seeds were incubated with P. poae strain S61 inoculant in a ratio of 1/5 (w/v) for 90 min.
Incubated seeds with the strain S61 were then germinated on wet sterile paper towels at 23°C under a day/ night cycle: 16 h/8 h until the cotyledons were completely expanded. And light intensity ranged from 2000 to 3000 lux. Then uniformly sized seedlings were transferred into the pots containing sterilized sandy soil and vermiculite (v/v: 1/1) in a plant growth chamber (MLR-351, SANYO, Moriguchi, Japan) under the following conditions: 16 h, 23°C (day)/8 h, 16°C (night), 2000∼5000 lux for 8 weeks. The sandy soil was collected from Hunyuan and irradiated at a dose of 10 KGy to kill microbes while the vermiculite was sterilized at 121°C for 20 min to exclude the effect of soil microbes on the seedling to exclude the interference of soil microbes. For each pot, 3-4 seedlings were planted and a routine watering was performed with sterile water once per week. The seedlings that were not incubated with the strain S61 were used as normal control and these treated with 300 mM MgCl 2 alone were used as vehicle control.

Drought stress and collection of plant materials
After grown in plant growth chamber for 8 weeks, most seedlings had 5∼6 true leaves. Again, uniformly sized seedlings were selected as raw materials for drought stress trial. For each trial group, the seedlings were randomly divided into two subgroups that were routinely watered with sterilized water and 20% PEG6000, respectively, for three weeks. The growth conditions were the same as described above. At the end, the aerial height, aboveground and belowground biomasses were first recorded. Then the 3rd to 5th leaves and root samples were individually collected, immediately frozen in liquid nitrogen and stored at −80°C for further analysis.
For quantification of ononin and calycosin-7-glucoside, 5 μL of extracts was injected into a RIGOL L-3000 Autosampling HPLC System (Puyuanjingdian, Beijing, China) and the separation was performed by the gradient elution program described in Pharmacopoeia of the People's Republic of China (Chinese Pharmacopoeia Commission 2015). And the chemical standards were bought from Jiangxi Bencao Tiangong (Nanchang, China). For leaf chlorophylls, the quantification was performed by a spectrophotometric method of . In order to determine malondialdehyde (MDA) content, TBA method was applied using a commercial assay kit (Cat. No, A003-1) that was bought from Nanjing Jiancheng (Nanjing, China).

Data analysis
For each experiment, the results were presented as the mean ± standard deviation (SD) of data from at least triplicates. Statistical evaluation was performed using one-way ANOVA, followed by Tukey's multiple-comparison test. All the statistical analyses were performed using the software GraphPad Prism 7.01 (California, USA), a P-value of <.05 was considered as significant difference.

Results
Stress tolerance and production of indoleacetic acid (IAA) of P. Poae strain S61 Drought and salt stress are the two major kind of abiotic stress throughout the world. In addition, soil acidity is an extended edaphic condition in culturable lands over the entire globe, and is also accepted as a major limited factor for legume productivity (von Uexküll and Mutert 1995) while a primary analysis showed that soil pH of the production area Hunyuan of Astragali Radix was ranged from 8.05-8.26 (supplemental Table S1). Thus, the growth performance P. Poae strain S61 was firstly investigated under different stress levels of salinity, desiccation and acidity and presented in Figure 1. Specifically, the strain was able to grow in the liquid medium ranged from pH 5.0-9.0, but the biomass at pH 5.0 was significantly reduced relative to the biomass at the other pH values examined (Figure 1(a)). As indicated in Figure 1(b), the strain was able to grow in the medium containing up to 7% NaCl and the adding of 2% NaCl exhibited improved growth performance. The influence of PEG6000 was presented in Figure 1(c), demonstrating that the strain S61 could tolerate the desiccation regime of 20% PEG6000 and adding less than 5% PEG6000 into the culture medium had no significant inhibitory effect on the strain growth.
As described above, the stress conditions including pH 5.0, 7% NaCl and 20% PEG6000 were nearly to the limitations that the strain was able to survive. The growth performance and IAA production of the strain were dynamically tracked under these extreme conditions and presented in Figure 2. When cultured in the medium with pH value 5.0, the strain exhibited a similar growth pattern to the control, suggesting that the medium pH slightly inhibited the strain growth Figure 1. The growth performance of P. Poae strain S61 under stress conditions. Absorbance at the wavelength 600 nm of the culture was respectively obtained by adjusting the medium acidity to variable values (a) and by adding different concentrations of NaCl (b) and PEG6000 (c) to the medium.
( Figure 2(a)). Meanwhile, adding 7% NaCl and 20% PEG6000 into the medium significantly inhibited the strain growth when compared with the normal control. From the incubation time point 13 h, an improved growth performance was observed when the strain was cultured in the medium containing 7% NaCl. Dynamic production of IAA under above extreme stresses was presented in Figure 2(b). It showed that the IAA production performed similar patterns to corresponding biomass that was obtained under the same stressed conditions excluding 20% PEG6000, the adding of which consistently had higher IAA levels than the addition of 7% NaCl. The figure also indicated that the IAA level reached the peak at the incubation time point 17 h regardless of the stress factor, coinciding with the maximum biomass at the time point. Since the production of IAA is very important for host plant growth and stress tolerance, it is reasonable to deduce that the strain S61 was more robust upon treatment of 20% PEG6000 relative to the application of 7% NaCl.
Growth-promoting effect of P. poae strain S61 on A. mongholicus seedlings under drought stress Drought is one of the most significant abiotic stresses that affect plant growth and secondary metabolism. For medical plants, they need to cope with adverse environmental and edaphic conditions exerted by their habitats, from which their growth, development and defense suffer. As the most natural inhabitants of diverse environments, endophytic consortia play key roles in amelioration of host abiotic stresses (Dupont et al. 2015). As shown in Figure 2, the adding of 20% PEG6000 severely inhibited the strain growth but induced relatively higher IAA production, suggesting that P. poae S61 was more robust and endurable to drought stress than salt stress. Thus, plant growth promotion of the strain was firstly explored in A. mongholicus seedlings by pouring 20% PEG6000. The result was listed in Figure 3, showing that the aboveground biomass (Figure 3(b)) was significantly decreased upon individual treatment of PEG6000 and the combination with the strain inoculation when compared with P. poae strain S61 inoculation alone. Although no significant difference in the aerial height or shoot biomass was observed between the trials and normal control, significant reduction in the combined trial of 20% PEG6000 and the strain inoculation was observed relative to the inoculation alone (Figure 3(a,b)). On the other hand, the combination of 20% PEG6000 with the inoculation significantly increased the root biomass (Figure 3 (c)) and root shoot ratio (Figure 3(d)), especially the latter index when compared to the treatment of 20% PEG6000 and the strain inoculation alone as well as the normal control. The result also indicated that the inoculation alone had the lowest root shoot ratio. Altogether, plant growth promotion of endophytic P. poae S61 was executed only when the seedlings grew under drought stress and focused on the belowground part.
As sessile organisms, plants have to tradeoff limited metabolic resources to grow or defend. Under stressed conditions, investment into defense leads to reduced growth (Wasternack 2017). As chlorophylls are essential components of photosynthetic system and derived from diterpenoids, impact on the seedling leaf chlorophylls was investigated and presented in Figure 4. Relative to the normal and vehicle controls, the combination of PEG6000 with P. poae S61 inoculation significantly decreased chlorophyll a content (Figure 4(a)). Meanwhile, individual application of PEG6000 and P. poae S61 inoculation kept chlorophyll a content at the same scale to the normal and vehicle controls. The figure also denoted that the combination of MgCl 2 with 20% PEG6000 obviously increased chlorophyll a when compared to the normal control. A similar influence on chlorophyll b was observed (Figure 4(b)). Taken together, the inoculation of P. poae S61 significantly reduced the contents of chlorophyll a and b in A. mongolicus seedlings under drought stress, suggesting that the strain has no benefits on the biosynthesis of essential chlorophylls in challenging environment.
Enhanced accumulations of bioactive compounds in the seeding roots obtained by the combination application of PEG6000 with P. poae S61 inoculation In Chinese pharmacopoeia, calycosin-7-O-glucoside and astragaloside IV are authorized as isoflavone and saponin indicators for quality evaluation of Astragali Radix, respectively. They are also major bioactive compounds contained in the herb (Zhang et al. 2014;Ju et al. 2018). In addition, ononin shares the same precursor formononetin with calycosin-7-glucoside and is another bioactive isoflavone widely distributed in legumes (Pan et al. 2007;Luo et al. 2018). Thus, the contents of ononin, calycosin-7-O-glucoside and astragaloside IV were determined in the seedling roots upon individual treatment of P. poae S61 inoculation and PEG6000 and their combination ( Figure 5). It demonstrated that the contents of calycosin-7-glucoside and ononin were significantly increased by the combination trail of 20% PEG6000 with P. poae S61 inoculation relative to the normal control. Meanwhile, the individual treatment of PEG6000 or the strain inoculation exhibited no obvious promoting effect on root accumulation of calycosin-7-O-glucoside. Conversely, P. poae strain S61 inoculation alone significantly decreased calycosin-7-O-glucoside content, suggesting that the promoting effect of P. poae S61 was executed only when the seedlings grew under drought stress condition. For astragaloside IV, the combined treatment of PEG6000 with the strain S61 inoculation resulted in a much lower concentration when compared with the other trials and controls, indicating that the promotion of P. poae strain S61 was not associated with saponin compounds under drought stress. On the contrary, the vehicle control roots contained significantly higher astragaloside IV content than the normal control, suggesting that the treatment of MgCl 2 was beneficial to astragaloside IV accumulation in the seedling roots under a routine watering management. Altogether, beneficial effect of P. poae S61 was mainly concentrated on root accumulation of isoflavone ccmpounds in A. mongolicus seedlings under droughtstressed condition. Figure 3. Effects of P. poae S61 inoculation, PEG6000 and their combination on A. mongholicus seedling growth. Note: The seeding growth performance was evaluated by follow parameters: the aerial height (a), aboveground biomass (b), belowground biomass (c) and the root shoot ratio (d). NC, MgCl 2 and S61 represented the normal control, vehicle controls and P. poae strain S61 inoculation alone, respectively. The groups of 20%PEG6000, 20%PEG6000&MgCl 2 and 20% PEG6000&S61 represented individual application of PEG6000 and combinations of PEG6000 with MgCl 2 and S61, respectively. The different letters above the bar indicate significant differences between the groups. Under drought stress conditions, plants produce excessive reaction oxygen species (ROS), thus result in an imbalance between ROS productivity and the ability to detoxify the reactive intermediates or to repair the resulting damage (Storz and Imalay 1999). And the damage caused by ROS can be evaluated by the lipid peroxidation of cellular membranes, using MDA as a chemical index of the process (Chugh et al. 2011). In order to understand underlying mechanism associated, MDA content in the seedling leaves and roots was determined and presented in Figure 6. Relative to the normal control, individual application of 20% PEG6000 slightly enhanced the leaf MDA level but had no significant effect on root MDA. On the contrary, the combination of 20% PEG6000 with the strain inoculation and the inoculation alone resulted in significantly higher MDA level in the leaves (Figure 6(a)) and significantly decreased MDA concentration in the roots (Figure 6(b)). Meanwhile, the seedling roots from a combined trial of 20%PEG6000 with MgCl 2 contained much lower MDA content. The result also demonstrated that the combination of 20% PEG6000 with the strain inoculation kept root MDA level at a moderate scale, which was higher than the combined application of 20% PEG6000 with MgCl 2 . Relatively, P. poae inoculation increased the leaf MDA content but decreased the root MDA to a moderate level, which was regardless of the drought stress, suggesting that the endophytic strain S61 might protect the medicinal part from the lipid peroxidation of cellular membranes in this herbal plant.

Discussion
It is well known that plants accumulate higher contents of secondary metabolites under drought stress. However, higher concentrations of secondary metabolites do not equate with their enhanced biosynthesis and accumulation in some cases. When drought-stressed plants exhibit reduced growth rate, they usually have lower biomass than the well-watered counterparts. In case of a similar biosynthetic rate of secondary metabolites, the concentrations of secondary metabolites will be enhanced due to lower biomass in drought-stressed plants (Paulsen and Selmar 2016). Hence, impact on the biomass and secondary metabolite content should be considered together in drought-stressed plants. In the current study, individual application of 20% PEG6000 and P. poae S61 incubation exerted no beneficial effect on the belowground biomass, calycosin-7-O-glucoside or ononin accumulation in the root tissue but their combination worked. The promoting effect was further confirmed by significant increasement in the amounts of calycosin-7-glucoside and ononin in the seedling roots (see supplemental Figure S1), demonstrating that endophytic bacterium P. Poae S61 promoted their accumulations in the roots only when the seedlings grew under drought-stressed condition. In addition, our work showed that all the trials had no promoting effect on astragaloside IV accumulation in the seedling roots excluding the vehicle control (ie MgCl 2 ). After 10 days of UV-B treatment, calycosin-7-O-glucoside accumulation was significantly enhanced in A. mongholicus plant roots (Liu et al. 2018). In addition, low temperature stress could induce calycosin-7-O-glucoside accumulation in different tissues of  A. mongholicus seedlings (Pan et al. 2007); ononin accumulation in the root tissue was improved in A. mongholicus plants under moderate salt stress (Liu et al. 2016). Thus, our work provided new evidence that endophytic bacteria residing A. mongholicus roots might play key roles in A. mongholicus plant growth and root accumulation of bioactive isoflavones, especially under drought stress.
In A. lancea, application of endophytic bacterium P. fluorescens increased oxygenous sesquiterpenoid content and diversity by triggering ROSs but kept the host MDA at the same level to the control, which was verified by the application of hydrogen peroxide and singlet oxygen (Zhou et al. 2016). Under mild drought treatment (10% PEG6000), fungal incubation of endophytic Acremonium strictum increased leaf MDA content of A. lancea plantlets to a moderate level, coinciding with obviously increased root shoot ratio and root fresh weigh, while no incubation contained much higher MDA content (Yang et al. 2014). Armada et al. (2016) draw a similar conclusion in Lavandula dentata by dual inoculation of AMF and Bacillus thuringiensis. In the current study, the combined trial of PEG6000 with P. poae S61 inoculation kept A. mongholicus seedling root MDA at a moderate scale but significantly enhanced leaf MDA level, demonstrating that the strain was able to alleviate root oxidative stress to some extent. Meanwhile, P. poae S61 inoculation enhanced A. mongholicus seedling root biomass and root shoot ratio under drought stress conditions. Taken improved accumulations of calycosin-7-O-glucoside and ononin into accounts in the roots, it was assumed that the promoting effect of endophytic P. poae S61 should be focused on the medicinal part of A. mongholicus by triggering shoot oxidative stress under drought-stressed conditions. And increased lipid peroxidation in the seedling leaves should be involved in the process. Further investigation should be done to understand the strain's beneficial effects assigned to the host plant growth and accumulation of bioactive isoflavones as well as underlying mechanism.

Disclosure statement
No potential conflict of interest was reported by the authors.

Notes on contributors
Haifeng Sun is Associate Professor at Shanxi University in the College of Chemistry and Chemical Engineering. Her research explores the roles and interactions of plant microbiota and green leaf volatiles as well as underlying mechanism in shaping the quality formation of herbal medicines. Her research aims to improve the quality of cultivated herbal plants by green and sustainable methods.
Liuli Kong is Professional Master Graduate Student at Shanxi University in the College of Chemistry and Chemical Engineering. Her research explores the beneficial effects of bacterial endophytes in plant growth and accumulation of bioactive compounds as well as underlying mechanism in medicinal parts of the herbal plants. Her research aims to find out beneficial endophytes that have potentials in the cultivation of herbal plants.
Huizhi Du is Professor at Shanxi University in the College of Chemistry and Chemical Engineering. Her research examines the transformation of ingredients in Chinese Traditional Medicine by bacteria. Her research aims to understand how plant microbiota affects the growth of herbal plants and the biosynthesis and accumulation of bioactive compounds in the medicinal parts.
Zhi Chai is Associate Professor at Shanxi University of Chinese Medicine in the department of Collaborative Innovation Center of Astragali Radix Resource Industrialization and Industrial Internationalization. He is mainly engaged in the research on planting and breeding of Astragali Radix. His research aims to identify excellent lines of Astragalus mongholicus that can grow in arid and semi-arid regions.
Jianping Gao is Professor at Shanxi Medical University in the College of Pharmacy. Her research clarifies the biosynthetic pathway and regulation of bioactive compounds, with a focus on polysaccharides in herbal plants. Her research aims to understand the quality formation and pharmacy of herbal medicine, such as Codonopsis Radix and Astragali Radix.
Qiufen Cao is Professor at Shanxi Academy of Agricultural Sciences in the Agricultural Biotechnology Research Centre. Her research is mainly concentrated on the identification of functional genes associated with key enzymes and transcriptional factors and breeding of herbal medicines as well as the biological control of plant diseases caused by continuous cropping. Her research aims to understand the molecular regulation of bioactive compound biosynthesis and cultivate herbal plants by environmentally friendly ways.