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Determination of Energetic and Geometric Properties of Plant Roots Specific Surface from Adsorption/Desorption Ishoterm  [PDF]
Grzegorz Jozefaciuk, Malgorzata Lukowska, Justyna Szerement
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.48187
Abstract:

Background and Aims: Structure and composition of plant roots surfaces are extremely complicated. Water vapor adsorption/desorption isotherm is a powerful tool to characterize such surfaces. The aim of this paper is to present theoretical approach for calculating roots surface parameters as adsorption energy, distribution of surface adsorption centers, as well as roots geometric and structure parameters as surface fractal dimension, nanopore sizes and size distributions on example of experimental isotherms of roots of barley taken from the literature. This approach was up to date practically not applied to study plant roots. Methods: Simplest tools of theoretical analysis of adsorption/desorption isotherms are applied. Results: Parameters characterizing energy of water binding, surface complexity and nanopore system of the studied roots were calculated and compared to these of the soils. Some possible applications of root surface parameters to study plant-soil interactions are outlined. Conclusions: Physicochemical surface parameters may be important for characterizing root surface properties, their changes in stress conditions, as well as for study and model plant processes. Physicochemical and geometrical properties of plant roots differ from these of the soils.

Pitfalls and Uncertainties of Using Potentiometric Titration for Estimation of Plant Roots Surface Charge and Acid-Base Properties  [PDF]
Grzegorz Jozefaciuk, Alicja Szatanik-Kloc, Malgorzata Lukowska, Justyna Szerement
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.513200
Abstract:

Amount and properties of roots surface charge are important for nutrient uptake and balance in plants. Roots surface charge markedly varies at different rizosphere conditions (particularly pH and ionic strength), which can markedly alter during vegetation season. Among recently available measuring methods, surface charge-pH dependence of roots (as well as other biological objects) is most easily evaluated by potentiometric titration. Use of this method is also easy at different ionic strengths. Potentiometric titration also allows for estimation of the distribution of charge generating surface groups. However, many applications of this method seem to be based either on incorrect methodical or theoretical approaches. In this paper we discuss the methodical and theoretical backgrounds of the titration method. Basing on experimental titration curves of roots of barley grown in nutrient solution, we show inconsistency of surface charge results obtained at different measuring conditions. Limitations of theoretical interpretations of the results are outlined also.

Rapid and accurate measurement of the specific surface area of snow using infrared reflectance at 1310 and 1550 nm  [PDF]
J.-C. Gallet,F. Domine,C. S. Zender,G. Picard
The Cryosphere Discussions , 2009,
Abstract: Even though the specific surface area (SSA) of snow is a crucial variable to determine the chemical and climatic impact of the snow cover, few data are available on snow SSA because current measurement methods are not simple to use in the field or do not have a sufficient accuracy. We propose here a novel determination method based on the measurement of the hemispherical reflectance of snow in the infrared using the DUFISSS instrument (DUal Frequency Integrating Sphere for Snow SSA measurement). DUFISSS uses 1310 and 1550 nm radiation provided by laser diodes, an integrating sphere 15 cm in diameter, and InGaAs photodiodes. For SSA<60 m2 kg 1, we use the 1310 nm radiation, reflectance is in the range 15 to 50% and the accuracy is 10%. For SSA>60 m2 kg 1, snow is usually of low to very low density (typically 30 to 100 kg m 3) and this produces artifacts caused by the e-folding length of light in snow being too long. We therefore use 1550 nm radiation for SSA>60 m2 kg 1. Reflectance is then in the range 5 to 12%, and the accuracy is 12%. No effect of crystal shape on reflectance was detected. We propose empirical equations to determine SSA from reflectance at both wavelengths, with that for 1310 nm taking into account the snow density. DUFISSS has been tested in the Alps to measure the snow area index (SAI) of the Alpine snowpack in a south facing area at 2100 m elevation. This was done by measuring the SSA, thickness and density of the seven main layers of the snowpack in just 30 min, and a value of 5350 was found, significantly greater than in Arctic and subarctic regions. DUFISSS can now be used to help study issues related to polar and Alpine atmospheric chemistry and climate.
Measurement of the specific surface area of snow using infrared reflectance in an integrating sphere at 1310 and 1550 nm
J.-C. Gallet,F. Domine,C. S. Zender,G. Picard
The Cryosphere , 2009,
Abstract: Even though the specific surface area (SSA) and the snow area index (SAI) of snow are crucial variables to determine the chemical and climatic impact of the snow cover, few data are available on the subject. We propose here a novel method to measure snow SSA and SAI. It is based on the measurement of the hemispherical infrared reflectance of snow samples using the DUFISSS instrument (DUal Frequency Integrating Sphere for Snow SSA measurement). DUFISSS uses the 1310 or 1550 nm radiation of laser diodes, an integrating sphere 15 cm in diameter, and InGaAs photodiodes. For SSA<60 m2 kg 1, we use the 1310 nm radiation, reflectance is between 15 and 50% and the accuracy of SSA determination is 10%. For SSA>60 m2 kg 1, snow is usually of low density (typically 30 to 100 kg m 3), resulting in insufficient optical depth and 1310 nm radiation reaches the bottom of the sample, causing artifacts. The 1550 nm radiation is therefore used for SSA>60 m2 kg 1. Reflectance is then in the range 5 to 12% and the accuracy on SSA is 12%. We propose empirical equations to determine SSA from reflectance at both wavelengths, with that for 1310 nm taking into account the snow density. DUFISSS has been used to measure the SSA of snow and the SAI of snowpacks in polar and Alpine regions.
Multielectrode Geoelectrical Tomography for the Quantification of Plant Roots  [cached]
Mariana Amato,Roberta Rossi,Giovanni Bitella,Stella Lovelli
Italian Journal of Agronomy , 2010, DOI: 10.4081/ija.2010.257
Abstract: The amount and spatial distribution of plant roots are crucial ecological features, and methods based on soil electrical resistivity (r) tomography (ERT) have been proposed for their non-destructive measurement. ERT allows to map root systems in conditions where the contrast of ρ between soil and roots is high, but the electrical behaviour of resistive or heterogeneous soils may interfere with root-borne effects and requires investigation. We studied the spatial distribution of ρ in different soil-root conditions to test the hypothesis that ERT would allow to detect the spatial distribution of plant roots even when low contrast between roots and background soil variation was expected. High-resolution 2-D and 3-D DC (Direct Current) soil resistivity tomograms were used to compare areas of high and low vegetation density in containers where bare soil (LM), was compared to a Medicago sativa L. (HM) stand, and in resistive soils where a stand of Arundo plinii Turra (HA) was compared with a bare soil (LA) and the area under the canopy of Olea europaea L. (HO) was compared with interrow areas (LO). Destructive measurements of root biomass per unit soil volume (RD), soil electrical conductivity (EC), stone content (S) and water content (q) were made in all treatments. Soil resistivity was significantly affected by vegetation density, with a resistive response in HM, HA and HO. The response was related to RD with significant univariate relationships and the spatial pattern of soil resistivity was dominated by roots and other resistive features like stones in all soils. This allows to conclude that ERT is able to detect plant-root effects even in the presence of a resistive background but resistive features interfere with the mesasurements and need to be taken into account. Abbreviations: ρ = in-situ soil electrical resistivity; EC = electrical conductivity of soil samples; θ = volumetric water content; RD = root biomass per unit soil volume; ERT = electrical resistivity tomography; 2-D = Two-dimensional; 3-D = three-dimensional; DC = Direct Current.
Population-specific gene expression in the plant pathogenic nematode Heterodera glycines exists prior to infection and during the onset of a resistant or susceptible reaction in the roots of the Glycine max genotype Peking
Vincent P Klink, Parsa Hosseini, Margaret H MacDonald, Nadim W Alkharouf, Benjamin F Matthews
BMC Genomics , 2009, DOI: 10.1186/1471-2164-10-111
Abstract: Differential expression and false discovery rate (FDR) analyses comparing populations of pi-L2 (i.e., incompatible population, NL1-RHg to compatible population, TN8) identified 71 genes that were induced in NL1-RHg as compared to TN8. These genes included putative gland protein G23G12, putative esophageal gland protein Hgg-20 and arginine kinase. The comparative analysis of pi-L2 identified 44 genes that were suppressed in NL1-RHg as compared to TN8. These genes included a different Hgg-20 gene, an EXPB1 protein and a cuticular collagen. By 12 h, there were 7 induced genes and 0 suppressed genes in NL1-RHg. By 3d, there were 9 induced and 10 suppressed genes in NL1-RHg. Substantial changes in gene expression became evident subsequently. At 8d there were 13 induced genes in NL1-RHg. This included putative gland protein G20E03, ubiquitin extension protein, putative gland protein G30C02 and β-1,4 endoglucanase. However, 1668 genes were found to be suppressed in NL1-RHg. These genes included steroid alpha reductase, serine proteinase and a collagen protein.These analyses identify a genetic expression signature for these two populations both prior to and subsequently as they undergo an R or S reaction. The identification of genes like steroid alpha reductase and serine proteinase that are involved in feeding and nutritional uptake as being highly suppressed during the R response at 8d may indicate genes that the plant is targeting. The analyses also identified numerous putative parasitism genes that are differentially expressed. The 1668 genes that are suppressed in NL1-RHg, and hence induced in TN8 may represent genes that are important during the parasitic stages of H. glycines development. The potential for different arrays of putative parasitism genes to be expressed in different nematode populations may indicate how H. glycines evolve mechanisms to overcome resistance.Plant parasitic nematodes are a major, but poorly understood agricultural problem, resulting in 157
Specific plant induced biofilm formation in Methylobacterium species
Rossetto, Priscilla B;Dourado, Manuella N;Quecine, Maria C;Andreote, Fernando D;Araújo, Welington L;Azevedo, Jo?o L;Pizzirani-Kleiner, Aline A;
Brazilian Journal of Microbiology , 2011, DOI: 10.1590/S1517-83822011000300006
Abstract: two endophytic strains of methylobacterium spp. were used to evaluate biofilm formation on sugarcane roots and on inert wooden sticks. results show that biofilm formation is variable and that plant surface and possibly root exudates have a role in methylobacterium spp. host recognition, biofilm formation and successful colonization as endophytes.
Swarming Behavior in Plant Roots  [PDF]
Marzena Ciszak, Diego Comparini, Barbara Mazzolai, Frantisek Baluska, F. Tito Arecchi, Tamás Vicsek, Stefano Mancuso
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0029759
Abstract: Interactions between individuals that are guided by simple rules can generate swarming behavior. Swarming behavior has been observed in many groups of organisms, including humans, and recent research has revealed that plants also demonstrate social behavior based on mutual interaction with other individuals. However, this behavior has not previously been analyzed in the context of swarming. Here, we show that roots can be influenced by their neighbors to induce a tendency to align the directions of their growth. In the apparently noisy patterns formed by growing roots, episodic alignments are observed as the roots grow close to each other. These events are incompatible with the statistics of purely random growth. We present experimental results and a theoretical model that describes the growth of maize roots in terms of swarming.
MEASUREMENT OF ROOT LENGTH DENSITY IN INTACT SAMPLES USING X-RADIOGRAPHY AND IMAGE ANALYSIS  [cached]
Alain Pierret,Chris J Moran,Colin B Mclachlan,John M Kirby
Image Analysis and Stereology , 2000, DOI: 10.5566/ias.v19.p145-149
Abstract: Measurement of root system attributes is of critical importance to understand and model plant growth. Root length density, the length of roots per unit volume of soil, is one of the important parameters required to understand plant performance. Measuring techniques currently in use to assess this parameter, such as for example core washing, are notoriously imprecise and labour-intensive. Roots and soil being inextricably linked, it is virtually impossible to separate them without loosing a significant amount of the root sample to be measured. This noticeably compromises the accuracy of washing techniques. For this reason, non-invasive measurement approaches are highly desirable. Here, a method based on the combination of X-radiography and image analysis is proposed as a new alternative for the measurement of root length density from intact samples. The successive steps of the method, from sampling to image acquisition are briefly described. A specific measurement algorithm, designed to account for the complex spatial arrangement of the roots within the samples is then presented and discussed in detail.
Abiotic stress responses in plant roots: a proteomics perspective  [PDF]
Dipanjana Ghosh,Jian Xu
Frontiers in Plant Science , 2014, DOI: 10.3389/fpls.2014.00006
Abstract: Abiotic stress conditions adversely affect plant growth, resulting in significant decline in crop productivity. To mitigate and recover from the damaging effects of such adverse environmental conditions, plants have evolved various adaptive strategies at cellular and metabolic levels. Most of these strategies involve dynamic changes in protein abundance that can be best explored through proteomics. This review summarizes comparative proteomic studies conducted with roots of various plant species subjected to different abiotic stresses especially drought, salinity, flood and cold. The main purpose of this article is to highlight and classify the protein level changes in abiotic stress response pathways specifically in plant roots. Shared as well as stressor-specific proteome signatures and adaptive mechanism(s) are simultaneously described. Such a comprehensive account will facilitate the design of genetic engineering strategies that enable the development of broad-spectrum abiotic stress-tolerant crops.
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