Root excretion and plant tolerance to cadmium toxicity - a review

Dong, Jing; Mao, Weiao; Zhang, G. P.; Wu, Feibo; Cai, Yuanfeng

doi:10.17221/2205-pse

Cited by 201 publications

(79 citation statements)

References 50 publications

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“…8c). Furthermore, our result in Laguna Colorada detected cadmium concentrations (Table 1) over the tolerance limit described for toxic levels (plants tolerance) in nature (Dong et al 2007). …”

Section: Physical Limitations and Dunaliella Speciessupporting

confidence: 55%

Extremophiles: photosynthetic systems in a high-altitude saline basin (Altiplano, Chile)

2016

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Studies of different hypersaline systems have revealed various types of limitation. We evaluated the phototrophic microbial assemblages over a whole seasonal cycle (wet vs dry) in the Salar de Alconcha, a high-altitude (4250 m altitude) saline basin. Phototrophic microbial communities were obtained from contrasting ecotypes, and examined for the effects of proximity and salinity variations. We also analyzed pigment profiles pointing to photosynthetic activity. While taxonomic diversity was limited to three algal groups (chlorophytes, diatoms, and cyanobacteria) ecological preferences were highly variable. Physical limitations when the photosynthetic system turn drier (maintaining viability and stability) appear to be the most successful adaptation (constrained assemblages) to the extreme condition in the Altiplano. This suggests that phototrophic microorganisms rarely achieve optimal growth, and could only do so when rain events reduce salinity (e.g. austral summer). However, environmental condition over the salt crust (total salt concentration: 119.74 g l -1 ) was an important driver to algal biomass. Overall, dominated by Dunaliella salina (&18,000 cell ml -1 ) turning the water into a red-orange colored system (b-carotene); aplanospore cysts were observed only during the driest season (austral winter). Our results suggest specific restrictive environments (e.g. environmental dissimilarity in the physical landscape) for phototrophic microbial colonization in highaltitude saline systems quite dependent upon water availability (system on the edge). The present study is a contribution for a better understanding of both the ecology of extreme environments and polyextremophiles communities (phototrophs) that inhabit them. Active salars are considered to be useful analogs of ancient photosynthetic systems, currently very pressured by groundwater extraction. Thus, altering the volume of water through the basin would have negative consequences on the structure and dynamics of local communities, and also in the stability of ecosystem functions.

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Section: Physical Limitations and Dunaliella Speciessupporting

confidence: 55%

Extremophiles: photosynthetic systems in a high-altitude saline basin (Altiplano, Chile)

2016

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“…Root exudates can react with heavy metal ions and influence metal solubility, mobility, and phytoavailability (Nigam et al 2001;Dong et al 2007). Whether root exudates enhance the mobility of metals in soil or not, the key role of root exudates in this aspect is commonly attributed to their strong metal binding ability, especially LMWOAs in root exudates (Hinsinger 2001;Chiang et al 2006Chiang et al , 2011.…”

Section: Introductionmentioning

confidence: 99%

Root exudates from sunflower (Helianthus annuusL.) show a strong adsorption ability toward Cd(II)

Yang

Pan

2013

Journal of Plant Interactions

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Cd(II) adsorption of root exudates from sunflower (Helianthus annuus L.) seedling was investigated by Cd ionselective electrode, Fourier Transform Infrared spectroscopy, and fluorescence spectroscopy. Root exudates from Helianthus annuus L. had strong adsorption ability toward Cd(II). The adsorption process was pH-dependent and the maximum adsorption capacity, 150.8 mg g(1 , was observed at pH 7.0. Root exudates had pK a1 at 4.7 for carboxyl and pK a2 at 9.2 for phenolic, and amino groups. The aliphatic and aromatic (C (H) groups, amide III group, and the C ( 0O) (O and sulfonate groups were responsible for Cd(II) adsorption. The excitation emission matrix fluorescence spectroscopy showed protein-like substances participated in Cd adsorption and formed strong complexes, with conditional stability constants of 4.70 and 4.32, which is a little lower than that determined by potentiometric methods, 5.13. The strong Cd complexing ability of root exudates implies that root exudates may significantly affect mobility, toxicity, and phytoavailability of Cd. Cd binding of root exudates may be attributed to its interaction with the proteins, polysaccharides, and phenolic compounds in root exudates.

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“…The essential role of roots in reducing metal leaching through uptake or soil immobilization has already been demonstrated [41,42]. Matching the mobilizing effect of roots in rhizospheric soil [43,44], higher leaching with vegetation cover in uncontaminated pots is expected, compared with uncultivated controls. Root morphology (surface area, diameter, tip density) generally plays an important role in nutrient and metal accumulation, especially for the less mobile Cd [45], and better tolerance to contamination should be expected when root distribution is moved downwards, as found in Sonchus and Tragopogon.…”

Section: Plant Responses To Metal Contaminants and Perspectives For Pmentioning

confidence: 91%

Phytoremediation Opportunities with Alimurgic Species in Metal-Contaminated Environments

et al. 2016

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Alimurgic species are edible wild plants growing spontaneously as invasive weeds in natural grassland and farmed fields. Growing interest in biodiversity conservation projects suggests deeper study of the multifunctional roles they can play in metal uptake for phytoremediation and their food safety when cultivated in polluted land. In this study, the responses of the tap-rooted perennial species Cichorium intybus L., Sonchus oleracerus L., Taraxacum officinale Web., Tragopogon porrifolius L. and Rumex acetosa L. were studied in artificially-highly Cd-Co-Cu-Pb-Zn-contaminated soil in a pot-scale trial, and those of T. officinale and R. acetosa in critical open environments (i.e., landfill, ditch sediments, and sides of highly-trafficked roads). Germination was not inhibited, and all species showed appreciable growth, despite considerable increases in tissue metal rates. Substantial growth impairments were observed in C. intybus, T. officinale and T. porrifolius; R. acetosa and S. oleracerus were only marginally affected. Zn was generally well translocated and reached a high leaf concentration, especially in T. officinale (~600 mg¨kg´1¨dry weight, DW), a result which can be exploited for phytoremediation purposes. The elevated Cd translocation also suggested applications to phytoextraction, particularly with C. intybus, in which leaf Cd reached~16 mg¨kg´1¨DW. The generally high root retention of Pb and Cu may allow their phytostabilisation in the medium-term in no-tillage systems, together with significant reductions in metal leaching compared with bare soil. In open systems, critical soil Pb and Zn were associated with heavily trafficked roadsides, although this was only seldom reflected in shoot metal accumulation. It is concluded that a community of alimurgic species can serve to establish an efficient, long-lasting vegetation cover applied for phytoremediation and reduction of soil metal movements in degraded environments. However, their food use is not recommended, since leaf Cd and Pb may exceed EU safety thresholds.

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Root excretion and plant tolerance to cadmium toxicity - a review

Cited by 201 publications

References 50 publications

Extremophiles: photosynthetic systems in a high-altitude saline basin (Altiplano, Chile)

Extremophiles: photosynthetic systems in a high-altitude saline basin (Altiplano, Chile)

Root exudates from sunflower (Helianthus annuusL.) show a strong adsorption ability toward Cd(II)

Phytoremediation Opportunities with Alimurgic Species in Metal-Contaminated Environments

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