Synergistic Plant–Microbe Interactions Between Endophytic Bacterial Communities and the Medicinal Plant Glycyrrhiza Uralensis F
Total Page：16
File Type：pdf, Size：1020Kb
Antonie van Leeuwenhoek https://doi.org/10.1007/s10482-018-1062-4 ORIGINAL PAPER Synergistic plant–microbe interactions between endophytic bacterial communities and the medicinal plant Glycyrrhiza uralensis F. Li Li . Osama Abdalla Abdelshafy Mohamad . Jinbiao Ma . Ariel D. Friel . Yangui Su . Yun Wang . Zulpiya Musa . Yonghong Liu . Brian P. Hedlund . Wenjun Li Received: 22 December 2017 / Accepted: 2 March 2018 Ó Springer International Publishing AG, part of Springer Nature 2018 Abstract Little is known about the composition, including 20 genera and 35 species. The number of diversity, and geographical distribution of bacterial distinct bacterial genera obtained from root tissues communities associated with medicinal plants in arid was higher (n = 14) compared to stem (n = 9) and leaf lands. To address this, a collection of 116 endophytic (n = 6) tissue. Geographically, the diversity of cultur- bacteria were isolated from wild populations of the able endophytic genera was higher at the Tekesi herb Glycyrrhiza uralensis Fisch (licorice) in (n = 14) and Xinyuan (n = 12) sites than the Gongliu Xinyuan, Gongliu, and Tekesi of Xinjiang Province, site (n = 4), reflecting the extremely low organic China, and identified based on their 16S rRNA gene carbon content, high salinity, and low nutrient status of sequences. The endophytes were highly diverse, Gongliu soils. The endophytic bacteria exhibited a number of plant growth-promoting activities ex situ, including diazotrophy, phosphate and potassium sol- Electronic supplementary material The online version of ubilization, siderophore production, auxin synthesis, this article (https://doi.org/10.1007/s10482-018-1062-4) con- tains supplementary material, which is available to authorized and production of hydrolytic enzymes. Twelve endo- users. phytes were selected based on their ex situ plant growth-promoting activities for growth chamber Li Li and Osama Abdalla Abdelshafy Mohamad have assays to test for their ability to promote growth of contributed equally to this work. L. Li Á O. A. A. Mohamad Á J. Ma Á Y. Su Á Z. Musa Y. Wang Á Z. Musa Á Y. Liu Á W. Li (&) College of Life Science and Technology, Xinjiang Key Laboratory of Biogeography and Bioresource in Arid University, Urumqi 830046, China Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences (CAS), Urumqi 830011, W. Li China State Key Laboratory of Biocontrol and Guangdong e-mail: [email protected] Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat Sen University, L. Li Á A. D. Friel Á B. P. Hedlund (&) Guangzhou 510275, China School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154, USA e-mail: [email protected] O. A. A. Mohamad Institute for Post Graduate Environmental Studies, Environmental Science Department, Arish University, North-Sinai 45516, Egypt 123 Antonie van Leeuwenhoek G. uralensis F. and Triticum aestivum (wheat) plants. These endophytes are part of a broader strategy for Several strains belonging to the genera Bacillus sustainable agriculture because they may decrease (n = 6) and Achromobacter (n = 1) stimulated total environmental pollution due to fertilizers and other biomass production in both G. uralensis and T. chemical applications. Endophytic bacteria associated aestivum under low-nutrient conditions. This work is with medicinal plants in arid lands can adopt sophis- the first report on the isolation and characterization of ticated survival strategies to promote plant growth, endophytes associated with G. uralensis F. in arid alleviate abiotic stresses, aid in nutrient acquisition, lands. The results demonstrate the broad diversity of and enhance systemic resistance and tolerance to endophytes associated with wild licorice and suggest disease (Boor 2006; Daffonchio et al. 2015). Never- that some Bacillus strains may be promising candi- theless, despite the considerable body of knowledge of dates for biofertilizers to promote enhanced survival the associations between endophytes and crop plants and growth of licorice and other valuable crops in arid (Wemheuer et al. 2017), much less is known of the environments. diversity of bacterial communities associated with plants inhabiting arid lands, particularly medicinal Keywords Biodiversity Á Plant growth-promoting plants. bacteria Á Glycyrrhiza uralensis Á Endophytic bacteria Á Medicinal plants are receiving global attention Arid lands-environmental microbiology because traditional medicines are often effective and easily available alternatives to pure pharmaceuticals. Medicinal plants are used worldwide as remedies for various diseases, including gastrointestinal symptoms, Introduction asthma, skin disorders, respiratory and urinary prob- lems, and hepatic disease (Cushnie et al. 2014). It is Endophytic bacteria are ubiquitous microorganisms well known that medicinal plants having an ethnob- that reside within healthy plant tissues (Gasser et al. otanical history may harbor an endophytic micro- 2011; Malfanova et al. 2011). These microorganisms biome that can synthesize a diverse array of bioactive are often hypothesized to help their hosts by producing compounds under conditions that are stressful to the resources that afford protection and facilitate survival host plant (Bajguz 2007). Bioactive compounds pro- of the host plant (Sa´nchez-Lo´pez et al. 2017). There- duced during endophyte-herb symbiosis can also fore, a better understanding of plant–microbe interac- affect plant-associated microbial communities and tions with respect to the physicochemical environment their physiological functions (Strobel et al. 2004). may provide insights into the microbial ecology of The genus Glycyrrhiza, commonly known as plant-associated endophytes (Islam et al. 2016; Patil licorice, comprises approximately 30 species includ- et al. 2016). The plant-associated microbiome consists ing Glycyrrhiza glabra, Glycyrrhiza uralensis, Gly- of distinct microbial communities living in roots, cyrrhiza inflata, Glycyrrhiza aspera, and Glycyrrhiza stems, leaves and other tissues. Symbioses between korshinskii (Lewis et al. 2005). Licorice (Glycyrrhiza plants and endophytic bacteria are mutually beneficial uralensis Fisch.) is one of the most widely used plants through the exchange of metabolites and sharing of in food production, and it is also used as traditional physiological processes (Reinhold-Hurek and Hurek Chinese medicine. Licorice contains bioactive com- 2011). The plant provides endophytes with a pounds such as triterpene saponins, flavonoids, stable habitat while endophytic bacteria supply nutri- coumarins, and other phenolics (Zhang and Ye ents such as fixed nitrogen, soluble potassium, iron, 2009), but little is known of their endophytic and phosphate, and indole acetic acid (Liu et al. microflora. A better understanding of endophytic 2016, 2017;Sa´nchez-Lo´pez et al. 2017). microorganisms adapted to arid lands is of broad In recent years, there has been an increasing interest importance in arid land ecology and can be exploited in the characterisation and bioprospecting of growth- for biotechnological applications. Therefore, the promoting endophytes, broadening the scope for objectives of our study were as follows: (1) isolate innovative design of biofertilizers for different crops and identify endophytic bacteria associated with G. such as soy, canola, lentil, pea, radish, and wheat uralensis F.; (2) screen them for beneficial activities (Donate-Correa et al. 2005; Egamberdiyeva 2007). ex situ; and (3) evaluate their ability to stimulate 123 Antonie van Leeuwenhoek growth of the host plant and Triticum aestivum. To the Tissue samples were separately surface-sterilized in a best of our knowledge, this is the first report on the laminar air flow chamber by immersing them sequen- isolation, identification, and characterization of endo- tially, with shaking, in 0.1% Tween 20 for a few phytic bacteria associated with the medicinal plant G. seconds, 70% ethanol for 3 min, and 5% NaOCl for uralensis F. in an arid environment. 5 min. Subsequently, samples were rinsed in sterile distilled water 3–4 times for each step of surface sterilization. After 24 h of drying in a laminar air flow Materials and methods chamber, sterilized parts of the selected plants, including leaves, stems, and roots, were used for the Sample collection and chemistry analysis isolation of endophytes. Samples were cut into 0.5 cm long fragments under aseptic conditions and ground in Healthy-looking G. uralensis F. plants were randomly a sterilized blender. About 1 g of tissue homogenate collected in the summer of 2015 from their natural arid was weighed aseptically and macerated with a sterile habitats in Xinjiang province of China. The study - mortar and pestle, along with 9 mL sterile distilled sites were Xinyuan (N 43°23022900;E83°50024800), water, and then transferred to a sterile polypropylene Gongliu (N 43°37018800;E81°48078700), and Tekesi (N tube. After that, the tissue homogenate was cen- 43°19020500;E81°48060100), each within Xinjiang trifuged at 22009g for 5 min. The supernatant was Province (Fig. 1). Three healthy plants were collected collected and serially diluted to a final concentration from each site; plants were at least 2 m apart within an of 10-2 and 10-3 and then 100 lL of each dilution was area of 100 m2. Whole plants, including root systems plated in triplicate onto ten different isolation media (15–20 cm depth), were placed in Zip-loc bags, and (Table S2). The agar plates were incubated at 28 °C stored