Soil labile organic carbon fractions in rhizosphere soil in citrus plantations in the Three Gorges Reservoir Area

Jia, Guomei; Zhang, Baolin; Jin, Niu; Wang, Liming; Chen, Fangqing

doi:10.1007/s10457-015-9838-2

Cited by 4 publications

(6 citation statements)

References 41 publications

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“…As an alternative, the rhizobia that do not nodulate their host, along with the vast majority of other resident microbiota, can reasonably expect to survive on the exudates from the plant roots. It has been well-documented that the rhizosphere is far richer in carbon than the surrounding bulk soil (Chiu et al, 2002;Jia et al, 2015). Essentially, all plants release root exudates, and the propensity to seek areas rich in carbon and nitrogen sources would allow rhizobia to acquire nutrients regardless of the source plant.…”

Section: Evidence Against the Possibility Of Flavonoid Chemotaxis In mentioning

confidence: 99%

An Updated Perspective on Sinorhizobium meliloti Chemotaxis to Alfalfa Flavonoids

et al. 2020

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The symbiotic interaction between leguminous plants and their cognate rhizobia allows for the fixation of gaseous dinitrogen into bioavailable ammonia. The perception of hostderived flavonoids is a key initial step for the signaling events that must occur preceding the formation of the nitrogen-fixing organ. Past work investigating chemotaxis-the directed movement of bacteria through chemical gradients-of Bradyrhizobium japonicum, Rhizobium leguminosarum, and Rhizobium meliloti discovered chemotaxis to various organic compounds, but focused on chemotaxis to flavonoids because of their relevance to the symbiosis biochemistry. The current work sought to replicate and further examine Sinorhizobium (Ensifer) meliloti chemotaxis to the flavonoids previously thought to act as the principal attractant molecules prior to the initial signaling stage. Exudate from germinating alfalfa seedlings was analyzed for composition and quantities of different flavonoid compounds using mass spectrometry. The abundance of four prevalent flavonoids in germinating alfalfa seed exudates (SEs) was at a ratio of 200:5:5:1 for hyperoside, luteolin, luteolin-7-glucoside, and chrysoeriol. Using quantitative chemotaxis capillary assays, we did not detect chemotaxis of motile S. meliloti cells to these, and two other flavonoids identified in seed exudates. In support of these findings, the flavonoid fraction of seed exudates was found to be an insignificant attractant relative to the more hydrophilic fraction. Additionally, we observed that cosolvents commonly used to dissolve flavonoids confound the results. We propose that the role flavonoids play in S. meliloti chemotaxis is insignificant relative to other components released by alfalfa seeds.

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Section: Evidence Against the Possibility Of Flavonoid Chemotaxis In mentioning

confidence: 99%

An Updated Perspective on Sinorhizobium meliloti Chemotaxis to Alfalfa Flavonoids

et al. 2020

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“…The results of some recent studies on the WLFZ showed that the stability of aggregates decreases as hydrological stress increases [18,31,32]. However, studies on the impacts of WLF on the carbon sequestration of different aggregates are still lacking [33].…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, understanding the alternations of SOC in the wetland in the WLFZ is extremely important for the global carbon cycle [34]. However, the background value of SOC is large, and it is difficult to respond quickly to alternations in soil carbon and environment [33]. According to the difficulty of SOC oxidation, Chan et al divided organic carbon into four fractions [35].…”

Section: Introductionmentioning

confidence: 99%

“…Hence, the study of labile carbon in the WLFZ is crucial for the global carbon cycle [38]. However, unfortunately, there are fewer studies on the labile carbon fraction in different aggregates than on the total SOC dynamics in different aggregates in the WLFZ [33]. Too little research of this was becoming a severe impediment to understanding causes affecting SOC sequestration in the WLFZ of the TGR.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Water-Level Fluctuation on Soil Aggregates and Aggregate-Associated Organic Carbon in the Water-Level Fluctuation Zone of the Three Gorges Reservoir, China

Sun,

Liu,

Tang

et al. 2024

Land

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Water-level fluctuation (WLF) can destroy soil aggregates and induce soil organic carbon (SOC) loss, potentially triggering impacts on the concentration of atmospheric carbon dioxide. However, responses of soil aggregate content and aggregate-associated organic carbon to WLF have not been well studied, especially in the water-level fluctuation zone (WLFZ) of the Three Gorges Reservoir (TGR). Therefore, samples from different elevations (145 m, 155 m and 165 m) in the WLFZ of the TGR were collected for experiments. The wet sieving method was used to divide soil into silt and clay (<0.053 mm), micro-aggregate (0.053–0.25 mm) and macro-aggregate (>0.25 mm). The K2Cr2O7-H2SO4 oxidation method was used to measure total SOC content in different soil aggregates. A modified Walkley and Black method was used to measure labile carbon in different soil aggregates. Results showed that macro-aggregate content substantially decreased, while micro-aggregate content remained stable and silt and clay fraction accumulated with a decrease in water-level elevations. Moreover, total SOC content and labile carbon in macro-aggregate were obviously higher than those in the micro-aggregate and the silt and clay fraction. Macro-aggregate contributed the most to SOC sequestration, while micro-aggregate contributed the least, and the contribution of macro-aggregate increased with a decrease in water-level elevations. We concluded that the macro-aggregate was the most active participant in the SOC sequestration process, and preferentially increasing the macro-aggregate content of the lowest water-level elevation was conducive to an improvement in soil carbon sequestration potential and would mitigate climate change.

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“…Soil active organic carbon components are composed of oxidized carbon (ROC) and water-soluble organic carbon (WSOC). ROC is a very abundant active organic carbon component, including easily decomposed humus and polysaccharides (Jia et al, 2015). Humus contains a large number of carboxyl and phenolic hydroxyl acid groups (Bai et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Activation and tolerance of Siegesbeckia Orientalis L. rhizosphere to Cd stress

Xie

Zhang

et al. 2023

Front. Plant Sci.

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This experiment investigated the changes of rhizosphere soil microenvironment for hyperaccumulation-soil system under Cd stress in order to reveal the mechanism of hyperaccumulation and tolerance. Thus, Cd fractions, chemical compositions, and biochemical characteristics in rhizosphere soil of Siegesbeckia orientalis L. under Cd stress conditions of 0, 5, 10, 25, 50, 100, and 150 mg kg-1 were investigated through a root bag experiment, respectively. As a result, Cd induced the acidification of S. orientalis rhizosphere soil, and promoted the accumulation of dissolved organic carbon (DOC) and readily oxidizable organic carbon (ROC), which increased by 28.39% and 6.98% at the maximum compared with control. The percentage of labile Cd (acid-soluble and reducible Cd) in soil solution increased significantly (P < 0.05) from 31.87% to 64.60% and from 26.00% to 34.49%, respectively. In addition, rhizosphere microenvironment can alleviate the inhibition of Cd on soil microorganisms and enzymes compare with bulk soils. Under medium and low concentrations of Cd, the rhizosphere soil microbial biomass carbon (MBC), basal respiration, ammonification and nitrification were significantly increased (P < 0.05), and the activities of key enzymes were not significantly inhibited. This suggests that pH reduction and organic carbon (DOC and ROC) accumulation increase the bioavailability of Cd and may have contributed to Cd accumulation in S. orientalis. Moreover, microorganisms and enzymes in rhizosphere soils can enhance S. orientalis tolerance to Cd, alleviating the nutrient imbalance and toxicity caused by Cd pollution. This study revealed the changes of physicochemical and biochemical properties of rhizosphere soil under Cd stress. Rhizosphere soil acidification and organic carbon accumulation are key factors promoting Cd activation, and microorganisms and enzymes are the responses of Cd tolerance.

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Soil labile organic carbon fractions in rhizosphere soil in citrus plantations in the Three Gorges Reservoir Area

Cited by 4 publications

References 41 publications

An Updated Perspective on Sinorhizobium meliloti Chemotaxis to Alfalfa Flavonoids

An Updated Perspective on Sinorhizobium meliloti Chemotaxis to Alfalfa Flavonoids

Effects of Water-Level Fluctuation on Soil Aggregates and Aggregate-Associated Organic Carbon in the Water-Level Fluctuation Zone of the Three Gorges Reservoir, China

Activation and tolerance of Siegesbeckia Orientalis L. rhizosphere to Cd stress

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