Rhizosheath of sinai desert plants is a potential repository for associative diazotrophs

Othman, Amal A.; Amer, Wafaa M.; Fayez, M. B. E.; Hegazi, N. A.

doi:10.1016/j.micres.2004.05.004

Cited by 40 publications

(43 citation statements)

References 13 publications

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“…Both AMF and non‐AMF hyphae have been observed in some rhizosheaths, but the relative abundance and roles of root hairs and different fungal components in the enmeshment of sand particles in rhizosheaths is not clear (Goodchild & Myers 1987; Degens et al . 1996; Othman et al . 2004; Moreno‐Espindola et al .…”

Section: Discussionmentioning

confidence: 99%

“…These relatively little understood complexes of sand particles, root hairs, mucilage, and often fungal and bacterial components are thought to function in various ways to increase plant nutrient acquisition and/or water retention and uptake within the grass rhizosphere. Rhizosheaths maintain higher moisture content, microbial densities and nitrogen concentration than surrounding soil and facilitate water movement across the soil–root interface (Young 1995; North & Nobel 1997; Othman et al . 2004; Bhatnagar & Bhatnagar 2005; Bergmann et al .…”

Section: Introductionmentioning

confidence: 99%

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Variation in root system traits among African semi‐arid savanna grasses: Implications for drought tolerance

et al. 2012

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In arid to semi-arid grasslands and savannas, plant growth, population dynamics, and productivity are consistently and strongly limited by soil water and nutrient availability. Adaptive traits of the root systems of grasses in these ecosystems are crucial to their ability to cope with strong water and/or nutrient limitation and the increasing drought stress associated with ecosystem degradation or projected climate change. We studied 18 grass species in semi-arid savanna of the Kalahari region of Botswana to quantify interspecific variation in three important root system traits including root system architecture, rhizosheath thickness and mycorrhizal colonization. Droughttolerant species and shorter-lived species showed greater rhizosheath thickness and fine root development but lower mycorrhizal colonization compared to later successional climax grasses and those characteristic of wetter sites. In addition, there was a significant positive correlation between root fibrousness index and rhizosheath thickness among species and a weak negative correlation between root fibrousness index and mycorrhizal colonization.These patterns suggest that an extensive fine root system and rhizosheath development may be important complementary traits of grasses coping with drought conditions, the former aiding in the acquisition of water by the grass plant and the latter aiding in water uptake and retention, and reducing water loss in the rhizosphere. Within species, both rhizosheath development and mycorrhizal colonization were significantly greater in a wet year than in a year with below-average precipitation. The observed patterns suggest that the primary benefit of rhizosheath development in African savanna grasses is improved drought tolerance and that it is a plastic trait that can be adjusted annually to changing environmental conditions. The functioning of mycorrhizal symbiosis is likely to be relatively more important in infertile savannas where nutrient limitation is higher relative to water limitation.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Variation in root system traits among African semi‐arid savanna grasses: Implications for drought tolerance

et al. 2012

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“…Eight representative pure isolates of endo‐rhizobacteria ( Azotobacter chroococcum , Bacillus macerans , Bacillus circulans , Burkholderia cepacia , Enterobacter clocae , Enterobacter sakazakii , Klebsiella oxytoca and Pseudomonas luteola ) were obtained from the culture collection of the Department of Microbiology, Faculty of Agriculture, Cairo University, Giza, Egypt (Othman et al , ). They were initially inoculated into semisolid CCM culture medium, and aliquots of 100 µl from the resulting broth cultures were evenly spread on the surface of agar plates of the various tested culture media.…”

Section: Methodsmentioning

confidence: 99%

Plant powder teabags: a novel and practical approach to resolve culturability and diversity of rhizobacteria

Sarhan

Mourad

Hamza

et al. 2016

Physiologia Plantarum

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We have developed teabags packed with dehydrated plant powders, without any supplements, for preparation of plant infusions necessary to develop media for culturing rhizobacteria. These bacteria are efficiently cultivated on such plant teabag culture media, with better progressive in situ recoverability compared to standard chemically synthetic culture media. Combining various plant-based culture media and incubation conditions enabled us to resolve unique denaturing gradient gel electrophoresis (DGGE) bands that were not resolved by tested standard culture media. Based on polymerase chain reaction PCR-DGGE of 16S rDNA fingerprints and sequencing, the plant teabag culture media supported higher diversity and significant increases in the richness of endo-rhizobacteria, namely Gammaproteobacteria (Enterobacteriaceae) and predominantly Alphaproteobacteria (Rhizobiaceae). This culminated in greater retrieval of the rhizobacteria taxa associated with the plant roots. We conclude that the plant teabag culture medium by itself, without any nutritional supplements, is sufficient and efficient for recovering and mirroring the complex and diverse communities of rhizobacteria. Our message to fellow microbial ecologists is: simply dehydrate your plant canopy, teabag it and soak it to prepare your culture media, with no need for any additional supplementary nutrients.

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“…But, if adapted desert plants occurred, e.g. Panicum and Stipagrostis in Sinai or Reaumuria negevensis in Negev, they strongly shaped soil microbial diversity [12], [13]. However, all these investigations showed a unique and extraordinary microbial diversity in desert soils.…”

Section: Introductionmentioning

confidence: 99%

Desert Farming Benefits from Microbial Potential in Arid Soils and Promotes Diversity and Plant Health

et al. 2011

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BackgroundTo convert deserts into arable, green landscapes is a global vision, and desert farming is a strong growing area of agriculture world-wide. However, its effect on diversity of soil microbial communities, which are responsible for important ecosystem services like plant health, is still not known.Methodology/Principal FindingsWe studied the impact of long-term agriculture on desert soil in one of the most prominent examples for organic desert farming in Sekem (Egypt). Using a polyphasic methodological approach to analyse microbial communities in soil as well as associated with cultivated plants, drastic effects caused by 30 years of agriculture were detected. Analysing bacterial fingerprints, we found statistically significant differences between agricultural and native desert soil of about 60%. A pyrosequencing-based analysis of the 16S rRNA gene regions showed higher diversity in agricultural than in desert soil (Shannon diversity indices: 11.21/7.90), and displayed structural differences. The proportion of Firmicutes in field soil was significantly higher (37%) than in the desert (11%). Bacillus and Paenibacillus play the key role: they represented 96% of the antagonists towards phytopathogens, and identical 16S rRNA sequences in the amplicon library and for isolates were detected. The proportion of antagonistic strains was doubled in field in comparison to desert soil (21.6%/12.4%); disease-suppressive bacteria were especially enriched in plant roots. On the opposite, several extremophilic bacterial groups, e.g., Acidimicrobium, Rubellimicrobium and Deinococcus-Thermus, disappeared from soil after agricultural use. The N-fixing Herbaspirillum group only occurred in desert soil. Soil bacterial communities were strongly driven by the a-biotic factors water supply and pH.Conclusions/SignificanceAfter long-term farming, a drastic shift in the bacterial communities in desert soil was observed. Bacterial communities in agricultural soil showed a higher diversity and a better ecosystem function for plant health but a loss of extremophilic bacteria. Interestingly, we detected that indigenous desert microorganisms promoted plant health in desert agro-ecosystems.

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Rhizosheath of sinai desert plants is a potential repository for associative diazotrophs

Cited by 40 publications

References 13 publications

Variation in root system traits among African semi‐arid savanna grasses: Implications for drought tolerance

Variation in root system traits among African semi‐arid savanna grasses: Implications for drought tolerance

Plant powder teabags: a novel and practical approach to resolve culturability and diversity of rhizobacteria

Desert Farming Benefits from Microbial Potential in Arid Soils and Promotes Diversity and Plant Health

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