Root Exudation and Rhizosphere Biology

Walker, Travis S.; Bais, Harsh P.; Grotewold, Erich; Vivanco, Jorge M.

doi:10.1104/pp.102.019661

Cited by 1,253 publications

(741 citation statements)

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“…Water deficits in soil environment also influence solute transport (ion and nutrient uptake of plants) to larger extent, which effects on photosynthetic reactions in plant chloroplasts in many ways [117,120,131,135,[139][140][141][142][143][144][145][146][147]. This is the reason that ion homeostasis and redox state have been brought to attention [4][5][6][7][21][22][23][24][25][26][27][28][29][111][112][113][114][115][116][117][118][119]. The series of the above reactions and processes occurring at different soil-root biointerfaces is regulated and controlled by plant gene regulatory network system spatially and temporally on the basis of responding to plant developmental cues, through which plants can elegantly respond to the changing environment [8][9][10][11][12][13][14][15][16][17]…”

Section: Physiological Theories: Understanding Higher Plant Physiologmentioning

confidence: 99%

The mutual responses of higher plants to environment: Physiological and microbiological aspects

Zhen-Kuan

Wang

et al. 2007

Colloids and Surfaces B: Biointerfaces

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Section: Physiological Theories: Understanding Higher Plant Physiologmentioning

confidence: 99%

The mutual responses of higher plants to environment: Physiological and microbiological aspects

Zhen-Kuan

Wang

et al. 2007

Colloids and Surfaces B: Biointerfaces

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“…The 7 influence of moisture content on the production of exudates is instead neglected. This is motivated by 8 previous findings (Rovira, 1969;Walker et al, 2003) that have shown that exudate production reduces only 9 when the moisture content falls below the wilting point, a condition that is observed rarely in riparian areas. 10…”

Section: Soil Carbon 24mentioning

confidence: 92%

“…In 15 addition to litter and humus dissolution and mobilization, root exudates also contribute to labile DOM 16 content of soils. Organic compounds released from roots play a number of extremely important roles for 17 plant physiology, such as protection from environmental stresses (drought, parasites, toxic compounds, e.g., 18 metals), or plant-plant and plant-microbe communication (Rovira, 1969;Walker et al, 2003).The rates of 19 root exudates production are extremely variable and depend on environmental and climatic factors. In 20 experiments, it has been found that typically a fraction in the range 5-20% of the total photosynthesized C is 21 released to the rhyzosphere as exudates (Walker et …”

Section: Soil Carbon 24mentioning

confidence: 99%

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Analysis of carbon and nitrogen dynamics in riparian soils: Model development

Brovelli¹,

Batlle-Aguilar²,

Barry³

2012

Science of The Total Environment

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1The quality of riparian soils and their ability to buffer contaminant releases to aquifers and streams are 2 connected intimately to moisture content and nutrient dynamics, in particular of carbon (C) and nitrogen (N). 3A multi-compartment model -named the Riparian Soil Model (RSM) -was developed to help investigate 4 the influence and importance of environmental parameters, climatic factors and management practices on 5 soil ecosystem functioning in riparian areas. The model improves existing tools, in particular regarding its 6 capability to simulate a wide range of temporal scales, from days to centuries, along with its ability to predict 7 the concentration and vertical distribution of dissolved organic matter (DOM). It was found that DOM 8 concentration controls the amount of soil organic matter (SOM) stored in the soil as well as the respiration 9 rate. The moisture content was computed using a detailed water budget approach, assuming that within each 10 time step all the water above field capacity drains to the layer underneath, until it becomes fully saturated. A 11 mass balance approach was also used for nutrient transport, whereas the biogeochemical reaction network 12 was developed as an extension of an existing C and N turnover model. Temperature changes across the soil 13 profile were simulated analytically, assuming periodic temperature changes in the topsoil. Sustainable management of riparian soils is of primary importance to preserve natural ecosystem 3 functioning. Riparian zones are sources of ecosystem functions and services including biodiversity hotspots, 4 water quality enhancement, and recreation sites (Brinson et al., 1981;Naiman and Decamps, 1997). 5Throughout the world, the ecological condition of natural riparian systems has declined due to a number of 6 factors, including streamflow regulation, floodplain development, channelization, and the spread of non-7 native species (Naiman and Decamps, 1997;Naiman et al., 2005). Consequently, restoration of riparian areas 8 has become a global management priority (Hughes et al., 2005;Hughes and Rood, 2003; Webb and Erskine, 9 2003). 10 Soil ecosystem functioning is connected intimately to soil organic matter (SOM) turnover, a set of complex 11 and intertwined biological processes that recycle biotic residues (such as plant litter, dead organisms, etc.) to 12 inorganic molecules. Environmental and climatic factors affect decomposition rates, the biological activity of 13 the soil and ultimately SOM cycling (Laio et al., 2001;Porporato et al., 2003). Soil moisture has a direct 14 influence on the processes mediated by the soil biota (pedofauna, bacteria, fungi, etc.) because optimal 15 decomposition rates are achieved only in a narrow saturation range (Bell et al., 2008; Ju et al., 2006; 16 Porporato et al., 2003;Van Gestel et al., 1992). Owing to the strong dependence of ecological processes on 17 soil moisture, linear and non-linear interactions and feedbacks exist between hydrological processes and soil 18 ecosystem functionin...

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“…Root exudates are defined as any chemical or metabolite secreted by a plant's root environment (Walker et al, 2003). These include sugars, carbohydrates, amino and other organic acids, lipids, enzymes, and a variety of other substances (Walker et al, 2003).…”

Section: Root Exudatesmentioning

confidence: 99%

Phytoremediation of Weathered Petroleum in Groundwater by Arroyo Willows in Nutrient Amended On-Site Mesocosms

Bragg-Flavan¹

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A large-scale mesocosm study was conducted to determine if vegetation with willow trees enhances biodegradation and to evaluate the mechanisms of natural biodegradation of weathered petroleum compounds under field conditions. The mesocosms were designed to model conditions at a former oil field where mid-range petroleum distillates were used as a diluent for pumping crude oil contaminated the soil and groundwater at the site with petroleum compounds. Ten mesocosms were constructed at the field site using un-impacted soil and diluent-impacted groundwater from the site. Five of the mesocosms were planted with Arroyo Willow trees native to the field site and the other five served as controls without trees. Since these willow trees are phreatophytes, their roots are capable of consuming water from the water table. A previous study was conducted using these mesocosms, however the willow trees then were in poor condition.In this study, fertilizer was added to the mesocosms to promote healthy growth of the willows. Fertilizer was added equally to mesocosms with and without willow trees to avoid introducing bias. Groundwater was circulated through the mesocosms for two 109 to 126 days runs, while the total petroleum hydrocarbon (TPH) concentrations of the groundwater were measured periodically. Dissolved oxygen concentrations were also monitored in each of the mesocosms to determine if the willow trees had any impact on oxygen transfer to the subsurface.In the first run without nutrient amendments the trees did not enhance biodegradation.All the mesocosms started with an average TPH concentration of 6.3 mg/L and ended vi with a concentration of 1.0 mg/L. After this first run, nutrient amendments were added to all the mesocosms, resulting in healthy trees with robust growth. With healthy willow trees, the planted mesocosms resulted in a statistically significant increase in long-term biodegradation of dissolved-phase petroleum compounds. The planted mesocosms resulted in 29 percent more degradation. These results agree with prior lab studies using bench-scale microcosms with media from the former oil field which indicated that TPH concentrations after 100 days were lower in containers with willows or lupines compared to controls without plants. Microtox ® toxicity decreased for both planted and control mesocosms, showing no toxic root exudates or by-products.There are several potential mechanisms of the observed phytoremediation. Terminal restriction fragment analyses showed that the planted mesocosms had different microbial communities than the unplanted mesocosms. Thus, a possible mechanism of the phytoremediation is stimulation of a rhizobial microbial community that biodegrades petroleum compounds. The dissolved oxygen (DO) concentrations were actually lower in the planted mesocosms, possibly due to consumption of oxygen during biodegradation of root exudates. The reduced DO concentrations in the planted mesocosm discounts the possibility that the plants stimulated biodegradation by increasing oxygen transfer to the ...

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Root Exudation and Rhizosphere Biology

Cited by 1,253 publications

References 64 publications

The mutual responses of higher plants to environment: Physiological and microbiological aspects

The mutual responses of higher plants to environment: Physiological and microbiological aspects

Analysis of carbon and nitrogen dynamics in riparian soils: Model development

Phytoremediation of Weathered Petroleum in Groundwater by Arroyo Willows in Nutrient Amended On-Site Mesocosms

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