Vol.:(0123456789) 1 3 Environmental Sustainability (2018) 1:209–215 https://doi.org/10.1007/s42398-018-0020-4 SHORT COMMUNICATION Medicinal plants with phytotoxic activity harbour endophytic bacteria with plant growth inhibitory properties Vyacheslav Shurigin 1,2  · Kakhramon Davranov 1  · Stephan Wirth 2  · Dilfuza Egamberdieva 1,2  · Sonoko Dorothea Bellingrath‑Kimura 2 Received: 19 April 2018 / Revised: 13 July 2018 / Accepted: 18 July 2018 / Published online: 23 July 2018 © Society for Environmental Sustainability 2018 Abstract The cultivable endophytic bacteria associated with two medicinal plants Hypericum perforatum L. and Ziziphora capitata L. contrasting with phytotoxic activity were investigated. The phytotoxic activity of plant extracts, and bacterial metabolites on seed germination and seedling growth of tomato were evaluated. In comparison to Z. capitata, the extract of H. perforatum contains a higher content of phenolic compounds. The crude extract of H. perforatum inhibited germination of seeds and seedling growth of tomato, whereas Z. capitata extracts only slightly reduced these parameters. Interestingly, almost half of the endophytes associated with H. perforatum had an inhibitory efect on plant growth, whereas rarely any plant inhibitory efect was found among isolates from Z. capitata. All bacterial isolates from Z. capitata were able to stimulate plant growth, by 35–80%. In contrast, only fve isolates from H. perforatum caused signifcant improvement in plant growth (22–46%). The results showed that medicinal plants with higher phytotoxic activity were colonized with endophytic bacteria which inhibit plant growth and development. These fndings indicate that plant phytochemical constituents and activity determine the physiological properties of their endophytes. Keywords Medicinal plant · Phenolic compound · Endophytes · Plant growth · Phytotoxicity Introduction Medicinal plants synthesize various biologically active compounds such as alkaloids, favonoids, saponins, phe- nolics, tannins, essential oils, and other compounds and show wide range of biological activity (Puupponen-Pimiä et al. 2001; Varsha et al. 2013; Vashist and Sharma 2013). Several secondary metabolites in plants can act as allelo- chemicals to other plants, stimulating or inhibiting their growth and development. There are several reports on the bio-insecticidal and plant growth stimulating efects of plant extracts from certain herbal plants (Jbilou et al. 2008; Ma et al. 2012). Earlier, Angelini et al. (2003) found that essential oils of medicinal plants may pose inhibitory efects on growth of other plants by releasing allelopathic substances. Ali et al. ( 2010) reported that allelopathic compounds in plants such as polyphenols inhibit seed germination and plant growth. The composition of plant secondary metabolites is strongly afected by the endo- phytic microbes associated with the host plant (Brader et al. 2014; Chaparro et al. 2014; Hashem et al. 2016; Egamberdieva et al. 2016). The endophytes that colonise inside plant tissues produce various metabolites and stimu- late plant growth and protect host plant from soil borne pathogens (Egamberdieva et al. 2016, 2017a, b, 2018). They produce various biological active metabolites includ- ing phytohormones, enzymes, antifungal compounds, and volatile organic compounds (Davis et al. 2013; Cho et al. 2015). Bioactive secondary metabolites produced by endo- phytes may also assist the plants in chemical defence (Ji et al. 2009). According to the host-endophyte coevolution hypothesis, chemical compounds synthesized by plants resemble those with the endophytic metabolites (Kumar et al. 2012; Rai et al. 2014). The root-associated bacte- ria with antifungal activity were reported from medicinal plants Matricaria chamomilla L., and Calendula offici- nalis, known with antibacterial activity (Köberl et al. * Vyacheslav Shurigin slaventus87@inbox.ru 1 Faculty of Biology, National University of Uzbekistan, 100174 Tashkent, Uzbekistan 2 Leibniz Centre for Agricultural Landscape Research (ZALF), 15374 Müncheberg, Germany