Eleonora Rolli

Oases are desert-farming agro-ecosystems, where date palm (Phoenix dactylifera L.) plays a keystone role in offsetting the effects of drought and maintaining a suitable microclimate for agriculture. At present, abundance, diversity and... more

Oases are desert-farming agro-ecosystems, where date palm (Phoenix dactylifera L.) plays a keystone role in offsetting the effects of drought and maintaining a suitable microclimate for agriculture. At present, abundance, diversity and plant growth promotion (PGP) of date palm root-associated bacteria remain unknown. Considering the environmental pressure determined by the water scarcity in the desert environments, we hypothesized that bacteria associated with date palm roots improve plant resistance to drought. Here, the ecology of date palm root endophytes from oases in the Tunisian Sahara was studied with emphasis on their capacity to promote growth under drought. Endophytic communities segregated along a north-south gradient in correlation with geo-climatic parameters. Screening of 120 endophytes indicated that date palm roots select for bacteria with multiple PGP traits. Bacteria rapidly cross-colonised the root tissues of different species of plants, including the original Tunisian date palm cultivar, Saudi Arabian cultivars and Arabidopsis. Selected endophytes significantly increased the biomass of date palms exposed to repeated drought stress periods during a nine-months greenhouse experiment. Overall, results indicate that date palm roots shape endophytic communities that are capable to promote plant growth under drought conditions, thereby contributing an essential ecological service to the entire oasis ecosystem.

Publication Date: 2015

Publication Name: Environmental Microbiology Reports

Research Interests:
Microbiology and Ecology

Publication Date: 2013

Publication Name: BioMed Research International

Research Interests:
Soil, Biodiversity, Tunisia, Salinity, Bacteria, and 8 morePlant Roots, Biomed, Soil Microbiology, Rhizosphere, Chenopodiaceae, Microbiota, Plant Development, and Physiological Stress Markers

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Publication Date: 2014

Publication Name: SpringerPlus

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Publication Date: 2014

Publication Name: BioMed Research International

Research Interests:
Technology, Biodiversity, Biological Sciences, Phylogeny, Plants, and 6 morePlant Roots, Biomed, Soil Microbiology, Rhizosphere, Ecosystem, and Altitude

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Publication Date: 2010

Publication Name: Yeast

Research Interests:
Microbiology, Industrial Biotechnology, Saccharomyces cerevisiae, Yeast, Amino Acid Substitution Rates, and 2 moreGene Expression Regulation and Gene expression profiling

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Publication Date: 2012

Publication Name: PLoS ONE

Research Interests:
Agriculture, Multidisciplinary, Phylogeny, Bacteria, Cluster Analysis, and 10 morePlants, Droughts, Plant Roots, PLoS one, Soil Microbiology, Rhizosphere, Ecosystem, Capsicum, Physiological Stress Markers, and Metagenome

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Publication Date: 2013

Publication Name: Plant Signaling & Behavior

Research Interests:
Plant Biology, Reactive Oxygen Species, Bacteria, Water Stress, Droughts, and 5 morePlant Roots, Rhizosphere, Drought tolerance, Ecosystem, and Biochemistry and cell biology

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Publication Date: 2009

Publication Name: Molecular Biology of the Cell

Research Interests:
Morphogenesis, Cell separation, Biological Sciences, Saccharomyces cerevisiae, Mutation, and 4 moreGreen Fluorescent Protein, Cell Wall, Chitin, and Plasma Membrane

Publication Date: 2011

Publication Name: Molecular Biology of the Cell

Research Interests:
Molecular Biology, Biological Sciences, Saccharomyces cerevisiae, Cell Differentiation, Meiosis, and 5 moreEndocytosis, Polymerase Chain Reaction, Glucans, Cell Wall, and Cell Cycle Proteins

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The genetic diversity of a collection of 336 spore-forming isolates recovered from five salt-saturated brines and soils (Chott and Sebkhas) mainly located in the hyper-arid regions of the southern Tunisian Sahara has been assessed.... more

The genetic diversity of a collection of 336 spore-forming isolates recovered from five salt-saturated brines and soils (Chott and Sebkhas) mainly located in the hyper-arid regions of the southern Tunisian Sahara has been assessed. Requirements and abilities for growth at a wide range of salinities\ showed that 44.3 % of the isolates were extremely halotolerant, 23 % were moderate halotolerant, and 32.7 % were strict halophiles, indicating that they are adapted to thrive in these saline ecosystems. A wide genetic diversity was documented based on 16S-23S rRNA internal transcribed spacer fingerprinting profiles (ITS) and 16S rRNA gene sequences that clustered the strains into seven genera: Bacillus, Gracilibacillus, Halobacillus, Oceanobacillus, Paenibacillus, Pontibacillus, and Virgibacillus. Halobacillus trueperi was the most encountered species in all the sites and presented a large intraspecific diversity with a multiplicity of ITS types. The most frequent ITS type included 42 isolates that were chosen for assessing of the intraspecific diversity by BOX-PCR fingerprinting. A high intraspecific microdiversity was documented by 14 BOX-PCR genotypes whose distribution correlated with the strain geographic origin. Interestingly, H. trueperi isolates presented an uneven geographic distribution among sites with the highest frequency of isolation from the coastal sites, suggesting a marine rather than terrestrial origin of the strains. The high frequency and diversity of H. trueperi suggest that it is a major ecosystem-adapted microbial component of the Tunisian Sahara harsh saline systems of marine origin.