Our results revealed that the relative abundance of pathogens was higher in diseased plants than in healthy plants. In this study, we compared the soil properties and microbial composition of the rhizosphere soil and roots of healthy and bacterial wilt-infected tobacco plants to assess their potential influence on plant health. Our results reveal the capability of plants in desert ecosystems to stabilize their below ground microbial community under seasonal contrasting environmental conditions, minimizing the heterogeneity of the surrounding bulk sand and contributing to the overall holobiont resilience under poly-extreme conditions.Ĭharacterizing the microbial communities associated with soil-borne disease incidence is a key approach in understanding the potential role of microbes in protecting crops from pathogens.
The microbiome-stabilization mediated by the plant host acts to consistently retain beneficial bacteria with multiple plant growth promoting functions, including those capable to produce EPS, which increase the sand water holding capacity ameliorating the rhizosheath micro-environment. The rhizosheath–root system bacterial communities are consistently dominated by Actinobacteria and Alphaproteobacteria and form distinct bacteria communities from those of bulk sand in the two seasons. On the contrary, the bacterial community associated with the rhizosheath–root system and its interactome remain stable and, unlike the bulk sand, are unaffected by the seasonal environmental variations. The plant responds to the harsh environmental conditions of the summer by increasing the abundance and diversity of extracellular polymeric substances (EPS) compared to the winter. The belowground rhizosheath–root system has higher nutrient and humidity contents, and cooler temperatures than the surrounding sand. Here, we examined the bacterial microbiota associated with this structure and its surrounding sand in the desert speargrass Stipagrostis pungens under the contrasting environmental conditions of summer and winter in the Sahara Desert. However, these extreme ecosystems host unique microenvironments, such as the rhizosheath–root system of desert speargrasses in which biological activities and interactions are facilitated by milder conditions and reduced fluctuations.
In hot deserts daily/seasonal fluctuations pose great challenges to the resident organisms.
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