Warming increases hotspot areas of enzyme activity and shortens the duration of hot moments in the root-detritusphere

Ma, Xiaomin; Razavi, Bahar S.; Holz, Maire; Blagodatskaya, Еvgenia; Kuzyakov, Yakov

doi:10.1016/j.soilbio.2017.01.009

Cited by 69 publications

(29 citation statements)

References 59 publications

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“…As chemical protection and physical protection have different mechanisms, their

Q_{10}^{prot}

is different from each other as well. Increasing temperature can weaken the protection intensity of organomineral interactions because higher temperature may enhance the activity of specific microbial groups and enzymes (Ma, Razavi, Holz, Blagodatskaya, & Kuzyakov, ; Razavi et al, ), leaving the protected C available for microorganisms. Furthermore, Conant et al () reported that increasing temperature can reduce mineral absorption and the strength of H‐bounding as well as van der Waals forces.…”

Section: Discussionmentioning

confidence: 99%

“…As chemical protection and physical protection have different mechanisms, their Q prot 10 is different from each other as well. Increasing temperature can weaken the protection intensity of organomineral interactions because higher temperature may enhance the activity of specific microbial groups and enzymes (Ma, Razavi, Holz, Blagodatskaya, & Kuzyakov, 2017;Razavi et al, 2017), leaving the protected C available F I G U R E 4 Dependence of turnover time of bulk soil (0-5 cm) and four fractions on mean annual temperature (MAT). LightF: light fraction; POM: particulate organic matter; HydrolysF: acid hydrolizable fraction; RecalcitF: recalcitrant fraction.…”

Section: Temperature Sensitivity Varies Across Soil Fractionsmentioning

confidence: 99%

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Temperature sensitivity of decomposition of soil organic matter fractions increases with their turnover time

et al. 2020

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Soil organic carbon (SOC) is an indicator of soil fertility. Global warming accelerates SOC decomposition, consequently, resulting in land degradation. Characterization of the response of SOC decomposition to temperature is important for predicting land development. A simulation model based on temperature sensitivity (Q10) of SOC decomposition has been used to predict SOC response to climate warming. However, uncertain Q10 leads to substantial uncertainties in the predictions. A major uncertainty comes from the interference of rainfall. To minimize this interference, we sampled surface (0–5 cm) soils along an isohyet across a temperature gradient in the Qinghai–Tibetan Plateau. The Q10 of bulk soil and the four soil fractions, such as light fraction (LightF), particulate organic matter (POM), hydrolyzable fraction (HydrolysF), and recalcitrant fraction (RecalcitF), were studied by 14C dating. Turnover time follows the order: LightF < POM < bulk soil < HydrolysF < RecalcitF. The Q10 follows the order: LightF (1.0) = POM (1.0) < HydrolysF (3.63) < bulk soil (5.93) < RecalcitF (7.46). This indicates that stable fractions are much more sensitive to temperature than labile fractions. We also suggest that protection mechanisms rather than molecular composition regulate SOC turnover. A new concept 'protection sensitivity' of SOC decomposition was proposed. Protection sensitivity relates to protection type and primarily controls Q10 variation. A simulation model based on the Q10 of individual fractions predicted SOC change and land development in the Qinghai–Tibetan Plateau in the next 100 years much effectively as compared to simulations based on one‐pool model (Q10 = 2) or bulk soil (Q10 = 5.93).

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“…As chemical protection and physical protection have different mechanisms, their

Q_{10}^{prot}

Section: Discussionmentioning

confidence: 99%

Section: Temperature Sensitivity Varies Across Soil Fractionsmentioning

confidence: 99%

Temperature sensitivity of decomposition of soil organic matter fractions increases with their turnover time

et al. 2020

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“…Unfortunately, the information about set‐up factors for 2‐D zymography in the literature is very limited. Published information pertains mostly to the type of camera (Liu et al, ; Ma, Razavi, Holz, Blagodatskaya, & Kuzyakov, ; Razavi et al, , ) and to the combination of camera type and source of the UV light (Spohn et al, ). We found only one detailed analysis of exposure times for 2‐D zymography of phosphatase activity in a recent publication by Giles et al ().…”

Section: Introductionmentioning

confidence: 99%

“…A review of recent publications showed that there is no general agreement on the precision of image calculations. An 8‐bit format was used by Spohn & Kuzyakov (, ) and Giles et al (), 16‐bit was used by Razavi et al (), Sanaullah et al () and Liu et al (), and 32‐bit images were used by Ma et al (). Original colour images taken by camera are 32‐bit, and their conversion to a smaller bit format may considerably reduce the accuracy of image calculations.…”

Section: Introductionmentioning

confidence: 99%

“…There is also no general agreement on how to deal with the background fluorescence intensity of zymography membranes. Some studies subtracted the grey values from zymograms corresponding to zero MUF concentration obtained during the calibration (Ma et al, ; Razavi et al, ; Sanaullah et al, ), whereas others set the intercept in the calibration curve to zero (Spohn & Kuzyakov, , ). Some studies mentioned the importance of background correction; however, they did not describe whether or how this was done (Giles et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Calibration of 2‐D soil zymography for correct analysis of enzyme distribution

Guber

Kravchenko

Razavi

et al. 2019

European J Soil Science

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Soil zymography is a new technique developed to visualize two‐dimensional distributions of enzyme activities. The method consists of incubating a membrane saturated with an enzyme‐specific fluorogenic substrate on a surface of the soil sample, followed by recording the membrane image generated by a fluorescent product (e.g. MUF: methylumbelliferone) in ultraviolet light. Despite its relative ease of use, performing zymography involves multiple user‐made decisions that might affect the accuracy of enzyme activity estimates. Therefore, unification of the zymography methodology is required for correct estimations and comparisons of various studies. We evaluated the following methodological aspects of the implementation of zymography: (a) camera settings and image processing, (b) effects of evaporation and (c) calibration procedures. Camera settings (shutter speeds or exposure time) affected the intensity of background fluorescence and signal‐to‐noise ratios (SNR). However, because their combined effects varied depending on MUF concentrations, light and camera setting need to be optimized for the expected range of MUF concentrations prior to zymography. Evaporation of MUF solution from the membrane had no effect on fluorescence. Relations between MUF concentration and intensity of fluorescence during calibrations demonstrated a saturated pattern and were strongly affected by image noise outside the optimal range (e.g. 8–14 μm MUF pixel−1). We developed a new calibration approach that is based on a piecewise linear regression. The new approach accounted for specific ranges of MUF concentration and uses nonuniformly saturated membranes, reflecting the real distribution of enzyme activities in soil. The new calibration algorithm eliminated biases of the standard calibration and resulted in greater accuracy in predicting MUF concentrations. Highlights We developed a new approach to calibration for 2‐D soil zymography. The approach accounted for spatial nonuniformity of soil zymograms. Standard calibration resulted in systematic underestimation of enzyme activity. Soil zymography requires pixel‐based calibration with nonuniformly saturated membranes.

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The effect of root hairs on rhizosphere phosphatase activity

Holz

Zarebanadkouki

Carminati

et al. 2020

J. Plant Nutr. Soil Sci.

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Background: Phosphatases in soil are of great importance for plant P acquisition. It is hypothesized that root hairs increase rhizosphere phosphatase activity as they release enzymes into soil and stimulate microbial activity. Methods: To test the effect of root hairs on soil phosphatase activity, we grew barley (Hordeum vulgare 'Pallas') wild type and its root-hairless mutant in rhizoboxes and determined phosphatase activity using soil zymography. Measurements were done at three moisture levels (30, 15, and 5% VWC). Rhizosphere phosphatase activity was estimated for the two genotypes and two locations along the root [root tip region (0-4 cm behind tip) and mature roots (> 7 cm behind tip)]. Results: Rhizosphere phosphatase activity was similar in the two locations along the root (root tip region vs. mature root parts). In contrast, rhizosphere phosphatase extension was two times larger for the root tip region of the wild type than for the mutant at 30% and 15% VWC. However, as phosphatase activities at the root surface of tips and mature root parts were slightly higher for the mutant than for the wild type, average enzyme activities were unaffected by the genotype. Conclusions: We conclude that the mutant seems to compensate for the lack of root hairs by increased phosphatase activity close to the root surface. However, the increased rhizosphere phosphatase extension for the wild type may be equally efficient as it allows P mobilization and uptake from large soil volumes.

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Warming increases hotspot areas of enzyme activity and shortens the duration of hot moments in the root-detritusphere

Cited by 69 publications

References 59 publications

Temperature sensitivity of decomposition of soil organic matter fractions increases with their turnover time

Temperature sensitivity of decomposition of soil organic matter fractions increases with their turnover time

Calibration of 2‐D soil zymography for correct analysis of enzyme distribution

The effect of root hairs on rhizosphere phosphatase activity

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