Effect of soil drying on mucilage exudation and its water repellency: a new method to collect mucilage

Ahmed, Mutez Ali; Holz, Maire; Woche, Susanne K.; Bachmann, Jörg; Carminati, Andrea

doi:10.1002/jpln.201500177

Cited by 41 publications

(49 citation statements)

References 19 publications

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“…comm.). Zea mays was selected representing a monocotyledonous species for which collection of larger amounts of mucilage from airborne brace (nodal) roots is an established procedure—we used the same cultivar as Ahmed et al (2015). Triticum aestivum was selected as a representative of monocotyledonous species with thin roots.…”

Section: Methodsmentioning

confidence: 99%

An efficient method for the collection of root mucilage from different plant species—A case study on the effect of mucilage on soil water repellency

Zickenrott

Woche

Bachmann

et al. 2016

J. Plant Nutr. Soil Sci.

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Root mucilage may play a prominent role in understanding root water uptake and, thus, there is revived interest in studying the function of root mucilage. However, mucilage research is hampered by the tedious procedures of mucilage collection. We developed a mucilage separator which utilizes low centrifugal forces (570 rpm) to separate the mucilage from seminal roots without the need of handling individual seeds or removing the germinated seeds from the tray/mesh to a centrifuge tube. For the different plant species, between 1 and 3.7 mL tray−1 of hydrated mucilage could be produced, with 6 trays being handled successively within 45 min. For Triticum aestivum, which showed a dry matter content of 0.5%, this was equivalent to 98.6 mg mucilage dry matter. The lowest total production was found for Zea mays with just 34 mg dry matter. The amounts of mucilage produced normalized to root tip agree well with literature data. The mucilage obtained by the new method was used to measure its effect on repellency of soil as this property directly relates to the phenomenon of lower rhizosphere soil water content during rewetting. It could be shown that repellency of the rhizosphere is affected by the quantity as well as by species‐dependent quality of mucilage in the rhizosphere. Among the species tested (Lupinus albus, Vicia faba, Zea mays, Triticum aestivum), the largest differences were observed between the two legumes. For Zea mays seminal root mucilage obtained with the new system was compared to mucilage of air born brace roots. The differences between these two mucilages, representing different root orders, indicate clearly that there is still a need for methods which enable the investigation of roots from older plants.

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Section: Methodsmentioning

confidence: 99%

An efficient method for the collection of root mucilage from different plant species—A case study on the effect of mucilage on soil water repellency

Zickenrott

Woche

Bachmann

et al. 2016

J. Plant Nutr. Soil Sci.

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“…Numerous studies used polygalacturonic acid (PGA) as a model substance for root mucilage to determine its influence on soil properties ( Zhang et al., ; Barré and Hallett , ; Mimmo et al., ; Peng et al., ). Mucilage's fast degradation rate ( Van Veelen et al., ) and in particularly its time‐consuming production and associated small yields ( Ahmed et al., ; Zickenrott et al., ) indeed required the use of model substances ( Brax et al., ). The choice of PGA as a model for mucilage is based on the high content of uronic acid measured in maize mucilage ( Morel et al., ) and on the similarities between mucilage and the calcium polygalacturonate network formed on garlic roots visualized with transmission and scanning electron microscopy ( Gessa and Deiana , , ).…”

Section: Introductionmentioning

confidence: 99%

“…Due to the experimental difficulty to isolate substantial amounts from root mucilage ( Zickenrott et al., ), chia seed mucilage ( Salvia hispanica L .) was used as natural mucilage: it is easily available in great quantities and shares gel properties such as viscosity relevant to seed, root and microbial exudates in soils ( Read and Gregory , ; Sutherland , ; Ahmed et al., ; Capitani et al., ). All substances were dialyzed against several concentrations of CaCl 2 ‐solutions.…”

Section: Introductionmentioning

confidence: 99%

Gel formation mechanism and gel properties controlled by Ca²⁺ in chia seed mucilage and model substances

Brax

Schaumann

Diehl

2018

J. Plant Nutr. Soil Sci.

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Polygalacturonic acid (PGA) is considered as a model substance for mucilage to study mucilage–soil interactions, assuming that the gel formation mechanism of mucilage is comparable to the one of PGA. However, some studies question the accepted hypothesis, which states that, like for PGA, this mechanism relies on cross‐links between uronic acid and calcium for mucilage. The aim of this study was therefore to understand the influence of the abundance and degree of esterification of uronic acids and the influence of calcium on the gel formation mechanism in mucilage as compared to model substances. The mucilage used was from chia seeds, as it is easily available in great quantity and has gel properties shared by root mucilage. Results reported here demonstrate that, while the gel formation mechanism of PGA relied on specific cross‐links with calcium and led to heterogeneous gels, low‐methoxy pectin (LMP) formed homogeneous calcium gels also characterized by nonspecific ionic interactions with calcium. On the contrary, despite similar uronic acid content to LMP, chia seed mucilage was mostly governed by weak electrostatic interactions between entangled polymer chains, which conferred the gel poor water retention. Addition of calcium reduced repulsion and molecular expansion, resulting in a reduction of the water content in chia seed mucilage. Finally, the discrepancies between PGA, LMP and chia seed mucilage discredit the use of PGA as model for chia seed mucilage. Comparison with root mucilage is still needed. This study offers the keys for further mechanistic understanding on the influence of mucilage on soil properties.

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“…While the polysaccharides contained in mucilage have a very high water holding capacity (McCully and Boyer, 1997), the lipids which are also contained (Read et al, 2003), can have a reverse effect when mucilage dries. It is therefore likely that mucilage is responsible for the observed rhizosphere hydrophobicity (Carminati, 2013;Ahmed et al, 2015;Benard et al, 2017). Fatty acids are composed of a hydrophilic and a hydrophobic tail of nonpolar fatty acid chains (C-H groups).…”

Section: Introductionmentioning

confidence: 99%

Spatial Distribution of Mucilage in the Rhizosphere Measured With Infrared Spectroscopy

Holz

Leue

Ahmed

et al. 2018

Front. Environ. Sci.

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Mucilage is receiving increasing attention because of its putative effects on plant growth, but so far no method is available to measure its spatial distribution in the rhizosphere. We tested whether the C-H signal related to mucilage fatty acids is detectable by infrared spectroscopy and if this method can be used to determine the spatial distribution of mucilage in the rhizosphere. Maize plants were grown in rhizoboxes filled with soil free of organic matter. Infrared measurements were carried out along transects perpendicular as well as axially to the root channels. The perpendicular gradients of the C-H proportions showed a decrease of C-H with increasing distance: 0.8 mm apart from the root center the C-H signals achieved a level near zero. The measured concentrations of mucilage were comparable with results obtained in previous studies, which encourages the use of infrared spectroscopy to quantitatively image mucilage in the rhizosphere.

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Effect of soil drying on mucilage exudation and its water repellency: a new method to collect mucilage

Cited by 41 publications

References 19 publications

An efficient method for the collection of root mucilage from different plant species—A case study on the effect of mucilage on soil water repellency

An efficient method for the collection of root mucilage from different plant species—A case study on the effect of mucilage on soil water repellency

Gel formation mechanism and gel properties controlled by Ca²⁺ in chia seed mucilage and model substances

Spatial Distribution of Mucilage in the Rhizosphere Measured With Infrared Spectroscopy

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Effect of soil drying on mucilage exudation and its water repellency: a new method to collect mucilage

Cited by 41 publications

References 19 publications

An efficient method for the collection of root mucilage from different plant species—A case study on the effect of mucilage on soil water repellency

An efficient method for the collection of root mucilage from different plant species—A case study on the effect of mucilage on soil water repellency

Gel formation mechanism and gel properties controlled by Ca2+ in chia seed mucilage and model substances

Spatial Distribution of Mucilage in the Rhizosphere Measured With Infrared Spectroscopy

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Gel formation mechanism and gel properties controlled by Ca²⁺ in chia seed mucilage and model substances