Cadmium accumulation by durum wheat roots in ligand-buffered hydroponic culture: uptake of Cd–ligand complexes or enhanced diffusion?

2003 ◽  
Vol 81 (7) ◽  
pp. 755-763 ◽  
Author(s):  
E J Berkelaar ◽  
B A Hale
Keyword(s):  
Durum Wheat ◽  
Chemical Speciation ◽  
Cadmium Accumulation ◽  
Root Surface ◽  
Diffusion Limitation ◽  
Root Tips ◽  
Cd Uptake ◽  
Wheat Roots ◽  
Enhanced Diffusion ◽  
Free Ion

The objectives of this study were to test the free ion model of Cd phytoavailability in solutions where the dissolved free ion was buffered by SO4 or EDTA and to examine if Cd2+ diffusion to roots might be limiting to its accumulation in roots. At similar Cd2+ activities, solutions that contained EDTA or a higher nominal SO4 concentration (with SO4 supplied as K2SO4, and more total Cd) resulted in greater accumulation of Cd by roots than predicted by the Cd2+ activity. These solutions were predicted using MINEQL+ (chemical speciation software) to contain greater concentrations of Cd complexes (CdEDTA2– or CdSO04 (aq)) in solution; when SO4 was supplied by MgSO4, the increase in Mg2+ suppressed enhanced accumulation of Cd. Estimates of diffusion of Cd to the roots through the boundary layer and flux of Cd across the root surface, for this study, were similar in magnitude across the range of solution Cd concentrations studied, particularly when Cd uptake was assumed to occur at the root tips only. We conclude that CdEDTA2– and CdSO04 (aq) could have alleviated this diffusion limitation by buffering Cd2+ at the root surface and (or) been taken up directly as a complex.Key words: bioavailability, cadmium, EDTA, SO4, durum wheat, speciation.

The relationship between root morphology and cadmium accumulation in seedlings of two durum wheat cultivars

2000 ◽  
Vol 78 (3) ◽  
pp. 381-387 ◽  
Author(s):  
Edward Berkelaar ◽  
Beverley Hale
Keyword(s):  
Durum Wheat ◽  
Surface Area ◽  
Root Morphology ◽  
Dry Weight ◽  
Cadmium Accumulation ◽  
Root Surface ◽  
Root Surface Area ◽  
Root Tips ◽  
Concentration Data ◽  
Cd Accumulation

Two cultivars of durum wheat (Triticum turgidum L.) with known, and different, grain-Cd accumulation were used to compare root tissue accumulation of Cd with root morphology. Six-day-old 'Kyle' and 'Arcola' seedlings were exposed to a range of Cd2 + concentrations (3.91 × 10-8 - 3.91 × 10-7 M) for 0-200 min, and root Cd contents for the two cultivars were compared with root morphological characteristics. 'Kyle' roots contained 35% less Cd per root system after 200 min of exposure and had less root surface area and fewer root tips than 'Arcola'. 'Kyle' roots also contained 30% less Cd per gram of dry weight than 'Arcola' roots after 200 min of exposure. 'Kyle' roots also had fewer root tips per unit of root dry weight and less surface area per unit of dry weight (DW) than 'Arcola'. When cadmium concentration data (µg·g-1 DW) were expressed per unit of root surface area (µg·cm-2) and per number of root tips (µg·tip-1), the difference in root Cd content between the two cultivars was smaller. These results suggest that greater root Cd content of 'Arcola' than 'Kyle' can be explained by differences in morphology, specifically that a greater surface area and more root tips in 'Arcola' leads to greater Cd accumulation in root tissue.Key words: cadmium accumulation, durum wheat, root morphology.

Effectiveness of complex inoculation of spring wheat with N[2] -fi xing bacteria Azospirillum brasilense and mold-antagonist Chaetomium cochliodes

2014 ◽  
Vol 1 (3) ◽  
pp. 57-61
Author(s):  
E. Kopylov
Keyword(s):  
Spring Wheat ◽  
Root Zone ◽  
Wheat Root ◽  
Root Surface ◽  
Atmospheric Nitrogen ◽  
Rhizospheric Soil ◽  
Chain Reaction ◽  
Wheat Roots ◽  
Chlorophyll A And B ◽  
Polymerase Chain

Aim. To study the specifi cities of complex inoculation of spring wheat roots with the bacteria of Azospirillum genus and Chaetomium cochliodes Palliser 3250, and the isolation of bacteria of Azospirillum genus, capable of fi xing atmospheric nitrogen, from the rhizospheric soil, washed-off roots and histoshere. Materials and meth- ods. The phenotypic features of the selected bacteria were identifi ed according to Bergi key. The molecular the polymerase chain reaction and genetic analysis was used for the identifi cation the bacteria. Results. It has been demonstrated that during the introduction into the root system of spring wheat the strain of A. brasilensе 102 actively colonizes rhizospheric soil, root surface and is capable of penetrating into the inner plant tissues. Conclusions. The soil ascomucete of C. cochliodes 3250 promotes better settling down of Azospirillum cells in spring wheat root zone, especially in plant histosphere which induces the increase in the content of chlorophyll a and b in the leaves and yield of the crop.

scholarly journals The occurrence of fungi on roots and stem bases of common wheat (Triticum aestivum ssp. vulgare L.) and durum wheat (Triticum durum Desf.) grown under two levels of chemical protection

2012 ◽  
Vol 64 (3) ◽  
pp. 93-102
Author(s):  
Irena Kiecana ◽  
Leszek Rachoń ◽  
Elżbieta Mielniczuk ◽  
Grzegorz Szumiło
Keyword(s):  
Durum Wheat ◽  
Common Wheat ◽  
Triticum Durum ◽  
Experimental Treatment ◽  
Bipolaris Sorokiniana ◽  
Wheat Roots ◽  
Chemical Protection ◽  
The Mean ◽  
Triticum Durum Desf ◽  
The University

Investigations were carried out in 2007-2009 on the plots of the Felin Experimental Station belonging to the University of Life Science in Lublin. The studies comprised two cultivation lines of durum wheat (<i>Triticum durum</i> L.): STH 716 and STH 717, as well as the 'Tonacja' cultivar of common wheat (<i>T. aestivum</i> ssp. <i>vulgare</i> L.). Two levels of chemical protection were applied in the cultivation: minimal and complex protection. Infection of wheat roots and stem bases was recorded in each growing season at hard dough stage (87 in Tottman's scale, 1987). After three years of study, the mean disease indexes for the analyzed wheat genotypes in the experimental treatment with minimal protection were 31.13, 30.43 and 38.83 for, respectively, the 'Tonacja' cultivar and the cultivation lines of <i>T. durum</i> STH 716 and STH 717. In the experimental combination with complex protection, after three years of study the disease indexes ranged from 25.26 (<i>T. durum</i> STH 716) to 30.83 (<i>T. durum</i> STH 717). The results of mycological analysis of diseased plants showed that <i>Fusarium</i> spp., especially <i>F. culmorum</i>, <i>F. avenaceum</i> as well as <i>Bipolaris sorokiniana</i> and <i>Rhizoctonia solani</i>, caused root rot and necrosis of wheat stem bases. The analyzed chemical protection levels did not significantly influence grain yield of the investigated genotypes of <i>T. aestivum</i> and <i>T. durum</i>.

scholarly journals Reducing Cadmium Accumulation in Plants: Structure–Function Relations and Tissue-Specific Operation of Transporters in the Spotlight

Plants ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 223 ◽  
Author(s):  
Xin Huang ◽  
Songpo Duan ◽  
Qi Wu ◽  
Min Yu ◽  
Sergey Shabala
Keyword(s):  
Structure Function ◽  
Current Knowledge ◽  
Cadmium Accumulation ◽  
Major Focus ◽  
Phloem Tissue ◽  
Cd Uptake ◽  
Major Health ◽  
Cd Accumulation ◽  
Tissue Specific

Cadmium (Cd) is present in many soils and, when entering the food chain, represents a major health threat to humans. Reducing Cd accumulation in plants is complicated by the fact that most known Cd transporters also operate in the transport of essential nutrients such as Zn, Fe, Mn, or Cu. This work summarizes the current knowledge of mechanisms mediating Cd uptake, radial transport, and translocation within the plant. It is concluded that real progress in the field may be only achieved if the transport of Cd and the above beneficial micronutrients is uncoupled, and we discuss the possible ways of achieving this goal. Accordingly, we suggest that the major focus of research in the field should be on the structure–function relations of various transporter isoforms and the functional assessment of their tissue-specific operation. Of specific importance are two tissues. The first one is a xylem parenchyma in plant roots; a major “controller” of Cd loading into the xylem and its transport to the shoot. The second one is a phloem tissue that operates in the last step of a metal transport. Another promising and currently underexplored avenue is to understand the role of non-selective cation channels in Cd uptake and reveal mechanisms of their regulation.

scholarly journals Effects of exogenous indole-3-acetic acid on the growth and cadmium accumulation of lettuce under cadmium stress

2019 ◽  
Vol 136 ◽  
pp. 07002
Author(s):  
Le Liang ◽  
Wanjia Tang ◽  
Xuemei Peng ◽  
Jing Lu ◽  
Han Liu ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Dry Weight ◽  
Cadmium Stress ◽  
Optimal Dose ◽  
Cadmium Accumulation ◽  
Cd Uptake ◽  
Cd Toxicity ◽  
Substantial Decline ◽  
Indole 3 Acetic Acid ◽  
Exogenous Iaa

Indole-3-acetic acid (IAA) plays crucial roles in plant growth and stress tolerance. In present study, the effects of spraying different concentrations (0, 25, 50, 100 and 200 μmol/L) of IAA on the growth and cadmium (Cd) accumulation in lettuce (Lactuca sativa) were investigated. The lettuce exposed to Cd exhibited a substantial decline in growth, and the Cd content of them significantly increased. Spraying exogenous IAA resulted in alleviating the inhibitory of Cd toxicity to lettuce. The dry weight in shoots of lettuce increased by spraying with IAA compared with the Cd treatment alone, but the dry weight of roots had no significantly differences. Although exogenous IAA increased the root Cd content, it significantly reduced shoot Cd content, indicating its role in Cd transport. Therefore, spraying IAA effectively alleviated Cd toxicity and reduced Cd uptake in the edible parts of lettuce, and the 100 μmol/L IAA was the optimal dose.

Rhythmic patterns of nutrient acquisition by wheat roots

2002 ◽  
Vol 29 (5) ◽  
pp. 595 ◽  
Author(s):  
Sergey Shabala ◽  
Andrew Knowles
Keyword(s):  
Root Zone ◽  
Root Hairs ◽  
Rhythmic Activity ◽  
Root Apex ◽  
Root Surface ◽  
Ion Flux ◽  
Nutrient Acquisition ◽  
Wheat Roots ◽  
Non Invasive ◽  
Functional Zone

Oscillatory patterns in H+, K+, Ca2+ and Cl- uptake were observed at different regions of the root surface, including root hairs, using a non-invasive ion flux measuring technique (the MIFE™ technique). To our knowledge, this is the first report of ultradian oscillations in nutrient acquisition in the mature root zone. Oscillations of the largest magnitude were usually measured in the elongation region, 2–4 mm from the root apex. There were usually at least two oscillatory components present for each ion measured: fast, with periods of several minutes; and slow, with periods of 50–80 min. Even within the same functional zone, the periods of ion flux oscillations were significantly different, suggesting that they are driven by some internal mechanisms located in each cell rather than originating from one ‘central clock pacemaker’. There were also significant changes in the oscillatory characteristics (both periods and amplitudes) of fluxes from a single small cluster of cells over time. Analysis of phase shifts between oscillations in different ions suggested that rhythmic activity of a plasma membrane H+-pump may be central to observed rhythmic nutrient acquisition by plant roots. We discuss the possible adaptive significance of such an oscillatory strategy for root nutrient acquisition.

scholarly journals In Situ Phylogenetic Structure and Diversity of Wild Bradyrhizobium Communities

2009 ◽  
Vol 75 (14) ◽  
pp. 4727-4735 ◽  
Author(s):  
J. L. Sachs ◽  
S. W. Kembel ◽  
A. H. Lau ◽  
E. L. Simms
Keyword(s):  
Host Species ◽  
Root Surface ◽  
Small Subset ◽  
Root Tips ◽  
Phylogenetic Structure ◽  
Pure Cultures ◽  
Nodulation Status ◽  
Host Infection ◽  
Root Surfaces

ABSTRACTBacteria often infect their hosts from environmental sources, but little is known about how environmental and host-infecting populations are related. Here, phylogenetic clustering and diversity were investigated in a natural community of rhizobial bacteria from the genusBradyrhizobium. These bacteria live in the soil and also form beneficial root nodule symbioses with legumes, including those in the genusLotus. Two hundred eighty pure cultures ofBradyrhizobiumbacteria were isolated and genotyped from wild hosts, includingLotus angustissimus,Lotus heermannii,Lotus micranthus, andLotus strigosus. Bacteria were cultured directly from symbiotic nodules and from two microenvironments on the soil-root interface: root tips and mature (old) root surfaces. Bayesian phylogenies ofBradyrhizobiumisolates were reconstructed using the internal transcribed spacer (ITS), and the structure of phylogenetic relatedness among bacteria was examined by host species and microenvironment. Inoculation assays were performed to confirm the nodulation status of a subset of isolates. Most recovered rhizobial genotypes were unique and found only in root surface communities, where little bacterial population genetic structure was detected among hosts. Conversely, most nodule isolates could be classified into several related, hyper-abundant genotypes that were phylogenetically clustered within host species. This pattern suggests that host infection provides ample rewards to symbiotic bacteria but that host specificity can strongly structure only a small subset of the rhizobial community.

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