In coming decades, drought is expected to expand globally owing to increased evaporation and reduced rainfall. Understanding, predicting, and controlling crop plants’ rhizosphere has the potential to manipulate its responses to environmental stress. Our plant growth-promoting rhizobacteria (PGPR) are isolated from a natural laboratory, ‘The Evolution Canyon’, Israel, (EC), from the wild progenitors of cereals, where they have been co-habituating with their hosts for long periods of time. The study revealed that commercial TM50 silica particles (SN) triggered the PGPR production of exopolysaccharides (EPS) containing D-glucuronate (D-GA). The increased EPS content increased the PGPR water-holding capacity (WHC) and osmotic pressure of the biofilm matrix, which led to enhanced plant biomass in drought-stressed growth environments. Light- and cryo-electron- microscopic studies showed that, in the presence of silica (SN) particles, bacterial morphology is changed, indicating that SNs are associated with significant reprogramming in bacteria. The findings encourage the development of large-scale methods for isolate formulation with natural silicas that ensure higher WHC and hyperosmolarity under field conditions. Osmotic pressure involvement of holobiont cohabitation is also discussed.

Currently, the problem of environmental pollution, especially in contaminated areas, is highly important. The study of the defense mechanisms of plants under salt stress (high salinity) is of considerable importance, given the conditions of current agricultural development and climate change. The aim of this study was to reveal the effect of salinity on Salix viminalis L. under field conditions at the Stebnyk tailing site in Ukraine. After 120 days of growth, the leaves, stems, and roots of S. viminalis were harvested to measure the antioxidant defense system of plants under salinity. Inhibition of S. viminalis growth was observed. We found that peroxidase, ascorbic acid, and proline mainly accumulated in the stems of S. viminalis under salinity conditions. However, in the roots, an increase in catalase activity and soluble sugars content was observed under salinity stress. Thus, the increase in the amount and changes in the activity of enzymes showed the involvement of the antioxidant system in the adaptation of S. viminalis to salinity. The data obtained in this study serve as a starting point for understanding the adaptive mechanisms of S. viminalis to salinity, particularly at the Stebnyk tailing. We believe our findings will support the use of plants in nature-based solutions and eco-engineering projects on saline and industrially polluted lands.

14In coming decades drought is expected to expand globally owing to increased 15 evaporation and reduced rainfall. In order to reduce the vulnerability of agricultural 16 systems we need to understand the crop plant growth environment. Understanding, 17 predicting and controlling the rhizosphere has potential to harness plant microbe 18 interactions, improve plant responses to environmental stress and mitigate effects of 19 climate change. Our plant growth-promoting rhizobacteria (PGPR) are isolated from 20 the natural laboratory 'Evolution Canyon' Israel (EC). The endophytic rhizobacteria 21 from the wild progenitors of cereals have been co-habituated with their hosts for long 22 periods of time. The study revealed that silica particles (SN) triggered the PGPR 23 production of exopolysaccharides (EPS) containing D-glucuronate (D-GA). This leads 24 to increased plant biomass accumulation in drought-stressed growth environments. 25The PGPR increased EPS content increases the water holding capacity (WHC) and 26 osmotic pressure of the biofilm matrix. Light-and electron-microscopic studies show 27 that in the presence of SN particles, bacterial morphology is changed, indicating that 28 SNs are associated with significant reprogramming in bacteria. 29The results here show that the production of EPS containing D-GA is induced by SN 30 treatment. The findings encourage formulation of cells considering microencapsulation 31 with materials that ensure higher WHC and hyperosmolarity under field conditions. 32Our results illustrate the importance of considering natural soil nanoparticles in the 33 application of PGPR. Osmotic pressure involvement of holobiont cohabitation is 34 discussed. 35 36 65 keeper for the bacterial drought tolerance enhancement (Timmusk, Kim et al. 2015).66 EC is a well described natural laboratory where microbes have co-habituated with 67 the hosts over a long period of time (Nevo 2012). Reciprocity between the organisms 68 is generally accepted (Gilbert, Bosch et al. 2015, Gilbert 2016, Rice, Kallonen et al. 69 2016, Gilbert 2019) and organisms that have co-evolved within the environment are 70 more robust to environmental stress situations (Robinson, Klein et al. 2018, Vega 71 2019). Microbes found in extreme habitats developed a different strategy to adapt to 72 such conditions through evolution. Holobiotic complex relationships in the given 73 framework, not robotic associations of genes, are becoming more and more accepted 74 in developmental and evolutionary biology (Gilbert, Bosch et al. 2015, Gilbert 2016, 75 Rice, Kallonen et al. 2016, Gilbert 2019). Hence, understanding the framework of 76 adaptation to extreme environments is gaining interest in a period of environment 77 change (Robinson, Klein et al. 2018, Vega 2019) . 78 Our recent plant nanointerface interaction research focusing on native soil particles 79 shows that silica nanoparticles (SN) promote PGPR attachment and plant 80 colonization, and this effect is translated into crop yield enhancement under stress 81 condit...

influence formation and distribution on the territory of groups of plants are described, among them the level of concentration of salts in substrate and humidification. The distribution of the identified types of plants by hybrid types and structure of the under ground shoots are considered. The role of vegetation in the processes of soil formation are discussed.