Mahmoud Gargouri1, Fatma Karray2, Asma Chebaane3, Najla Mhiri4, Laila Pamela Partida-Martínez5, Sami Sayadi6, Ahmed Mliki3. 1. Laboratory of Plant Molecular Physiology, Centre of Biotechnology of Borj-Cedria, PB.901, 2050 Hammam-Lif, Tunisia. Electronic address: mahmoud.gargouri@cbbc.rnrt.tn. 2. Laboratory of Environmental Bioprocesses, Centre of Biotechnology of Sfax, BP 1177, 3018 Sfax, Tunisia. Electronic address: fatma.karray@cbs.rnrt.tn. 3. Laboratory of Plant Molecular Physiology, Centre of Biotechnology of Borj-Cedria, PB.901, 2050 Hammam-Lif, Tunisia. 4. Laboratory of Environmental Bioprocesses, Centre of Biotechnology of Sfax, BP 1177, 3018 Sfax, Tunisia. 5. Laboratory of Microbial Interactions, Departamento de Ingeniería Genética, Centro de Investigación y de Estudios Avanzados (CINVESTAV), 36824 Irapuato, Mexico. 6. Centre for Sustainable Development, College of Arts and Sciences, Qatar University, Doha 2713, Qatar.
Abstract
AIMS: The effects of aridity on soil and water-use efficient (WUE) crop species are relatively well known. However, the understanding of its impacts on the dynamics of below-ground microorganisms associated with plant roots is less well understood. METHODS: To investigate the influence of increasing aridity on the dynamics of the fungal communities, samples from the root endosphere and rhizosphere associated with the prickly pear cactus trees (Opuntia ficus-indica) growing along the aridity gradient were collected and the internal transcribed spacer (ITS) were sequenced. The diversity and network analyses of fungal taxa were determined along with standard measurements of soil parameters. RESULTS: We found that (i) the fungal community exhibited similar alpha diversity and shared a set of core taxa within the rhizosphere and endosphere, but there was significant beta diversity differences; (ii) the relative abundance of major phyla was higher in the rhizosphere than in the endosphere; (iii) arbuscular endomycorrhizal colonization was highest in the humid climate and decreased under lower-arid, and was negatively correlated with increased concentration of Ca2+ in the soil; (iv) increased aridity correlated with increased connectivity of the soil microbial-root fungal networks in the arid soils, producing a highly cohesive network in the upper-arid area; and (v) distinct fungal hubs sculpt the fungal microbiome network structure in the rhizosphere and endosphere within each bioclimatic zone. CONCLUSIONS: Our findings highlight the importance of gradient analysis-based correlation network as a powerful approach to understand changes in the diversity, the dynamics, and the structure of fungal communities associated with the rhizosphere-endosphere interaction and led to the identification of microbes at each bioclimatic zone that are potentially involved in promoting the survival, protection, and growth of Opuntia trees. The variability of fungal hubs composition depending on plant compartment and bioclimatic zone will give key implications for the application of rhizospheric fungi and endophytes as microbial inoculants in agriculture, as well as in the conservation and restoration of cacti plants in arid and semi-arid lands against the backdrop of climate change. Overall, this study will enhance our understanding of the microbiomes'dynamic of CAM plants in nature.
AIMS: The effects of aridity on soil and water-use efficient (WUE) crop species are relatively well known. However, the understanding of its impacts on the dynamics of below-ground microorganisms associated with plant roots is less well understood. METHODS: To investigate the influence of increasing aridity on the dynamics of the fungal communities, samples from the root endosphere and rhizosphere associated with the prickly pear cactus trees (Opuntia ficus-indica) growing along the aridity gradient were collected and the internal transcribed spacer (ITS) were sequenced. The diversity and network analyses of fungal taxa were determined along with standard measurements of soil parameters. RESULTS: We found that (i) the fungal community exhibited similar alpha diversity and shared a set of core taxa within the rhizosphere and endosphere, but there was significant beta diversity differences; (ii) the relative abundance of major phyla was higher in the rhizosphere than in the endosphere; (iii) arbuscular endomycorrhizal colonization was highest in the humid climate and decreased under lower-arid, and was negatively correlated with increased concentration of Ca2+ in the soil; (iv) increased aridity correlated with increased connectivity of the soil microbial-root fungal networks in the arid soils, producing a highly cohesive network in the upper-arid area; and (v) distinct fungal hubs sculpt the fungal microbiome network structure in the rhizosphere and endosphere within each bioclimatic zone. CONCLUSIONS: Our findings highlight the importance of gradient analysis-based correlation network as a powerful approach to understand changes in the diversity, the dynamics, and the structure of fungal communities associated with the rhizosphere-endosphere interaction and led to the identification of microbes at each bioclimatic zone that are potentially involved in promoting the survival, protection, and growth of Opuntia trees. The variability of fungal hubs composition depending on plant compartment and bioclimatic zone will give key implications for the application of rhizospheric fungi and endophytes as microbial inoculants in agriculture, as well as in the conservation and restoration of cacti plants in arid and semi-arid lands against the backdrop of climate change. Overall, this study will enhance our understanding of the microbiomes'dynamic of CAM plants in nature.