Comparative analysis of Cd and Zn impacts on root distribution and morphology of Lolium perenne and Trifolium repens: implications for phytostabilization
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Backgrounds and aims
The phytostabilization potential of plants is a direct function of their root systems. An experimental design was developed to investigate the impact of Cd and Zn on the root distribution and morphology of Lolium perenne and Trifolium repens.
Seedlings were transplanted into columns filled with washed quartz and irrigated daily with Cd- or Zn-containing nutrient solutions during 1 month. Root biomass, root length density (RLD) and diameter were subsequently quantified as a function of depth. Pot experiments were also performed to quantify metal, lignin and structural polysaccharides concentrations as well as cell viability.
Lolium perenne accumulated Cd and Zn in the roots whereas T. repens was unable to restrict heavy metal translocation. Cadmium and Zn reduced rooting depth and RLD but induced thick shoot-borne roots in L. perenne. Cd-induced root swelling was related to lignification occurring in the exodermis and parenchyma of central cylinder. Hemicelluloses and lignin did not play a key role in root metal retention. Cadmium slightly reduced mean root cell viability whereas Zn increased this parameter in comparison to Cd.
Even though plant species like Lolium perenne and Trifolium repens may appear suitable for a phytostabilization scheme based on their shoot metal tolerance, exposure to toxic heavy metals drastically impairs their root distribution. This could jeopardize the setting up of phytostabilization trials. The metal-induced alterations of root system properties are clearly metal- and species-specific. At sites polluted with multiple metals, it is therefore recommended to first test their impact on the root system of multiple plant species so as to select the most appropriate species for each site.
KeywordsHeavy metal contamination Root distribution Root diameter Lignin and structural polysaccharides Lolium perenne Trifolium repens
The authors would like to thank Dr. Xavier Draye for his pertinent suggestions about the experimental design, as well as Thomas Dagbert for his technical assistance concerning the root cross-sections.
- Abràmoff MD, Magalhães PJ, Ram SJ (2004) Image processing with ImageJ. Biophoton Int 11:36–42Google Scholar
- Bidar G, Verdin A, Garcon G, Pruvot C, Laruelle F, Grandmougin-Ferjani A, Douay F, Shirali P (2008) Changes in fatty acid composition and content of two plants (Lolium perenne and Trifolium repens) grown during 6 and 18 months in a metal (Pb, Cd, Zn) contaminated field. Water Air Soil Pollut 192:281–291CrossRefGoogle Scholar
- Boisson J, Bouchardon JL, Carrey A, Charissou AM, Colpaert J, Faure O, Guérin V, Joulian C, Pottecher G, Remon E, Vangronsveld J (2009) Evaluation des performances de la phytostabilisation sur un grand site. 2e Rencontres Nationales de la Recherche sur les Sites et Sols Pollués, ADEME, ParisGoogle Scholar
- Chen G, Liu Y, Wang R, Zhang J, Owens G (2013) Cadmium adsorption by willow root: the role of cell walls and their subfractions. Environ Sci Pollut Res:1–8Google Scholar
- Deiana S, Manunza B, Palma A, Premoli A, Gessa C (2001) Interactions and mobilization of metal ions at the root-soil interface. In: Gobran GR, Wenzel WW, Lomobi E (ed) Trace elements in the rhizosphere. Academic Press, pp 127–148Google Scholar
- Kabata-Pendias A (2001) Trace elements in soils and plants, 3rd edn. CRC Press, Boca RatonGoogle Scholar
- Kapur JN, Sahoo PK, Wong ACK (1985) A new method for gray-level picture thresholding using the entropy of the histogram. Graph Model 29:273–285Google Scholar
- Lobet G, Draye X (2013) Novel scanning procedure enabling the vectorization of entire rhizotron-grown root systems. Plant Methods 9: doi:10.1186/1746-4811-9-1
- Lopareva-Pohu A, Verdin A, Garçon G, Lounès-Hadj Sahraoui A, Pourrut B, Debiane D, Waterlot C, Laruelle F, Bidar G, Douay F, Shirali P (2011) Influence of fly ash aided phytostabilisation of Pb, Cd and Zn highly contaminated soils on Lolium perenne and Trifolium repens metal transfer and physiological stress. Environ Pollut 159:1721–1729PubMedCrossRefGoogle Scholar
- Yoshida S, Forno DA, Cock JH, Gomez KA (1976) Laboratory manual for physiological studies of rice, 3rd edn. The International Rice Research Institute, ManilaGoogle Scholar
- Zhu XF, Lei GJ, Jiang T, Liu Y, Li GX, Zheng SJ (2012) Cell wall polysaccharides are involved in P-deficiency-induced Cd exclusion in Arabidopsis thaliana. Planta:1–9Google Scholar