Estimation of cadmium availability using transformed roots

Abstract

We have explored cultures of roots transformed by Agrobacterium rhizogenes to test the availability of cadmium in sewage sludges. The toxic effects of Cd and the kinetics of Cd accumulation were examined for three species of transformed roots, grown for 2 weeks in nutrient media, containing Cd as a salt.Roots of sugar beet (Beta vulgaris L.) were highly sensitive, while those of tobacco (Nicotiana tobaccum L.) and morning glory (Calystegia sepium R. Br) were more tolerant. Cd accumulation was higher in sugar beet and morning glory than in tobacco. We developed a non-sterile, 5-day procedure for testing the accumulation (an indication of availability) of Cd from sludge suspensions, using transformed roots of morning glory and tobacco. Cd accumulation varied with plant species and source of sludge. Ranking of Cd availability using this biological assay for Cd accumulation was confirmed by chemical tests with NH 4 acetate and EDTA. Results from transformed roots were also compared with those from normal, excised, tobacco roots and normal and transformed tobacco plantlets. No major alteration in Cd uptake was associated with genetic transformation. We thus demonstrated the feasibility of using transformed roots to estimate the availability of Cd in metal-contaminated materials like sewage sludges.

Assessing potential dietary toxicity of heavy metals in selected vegetables and food crops

“…Experiments using separately cultured organs also allow the metal accumulation properties of each organ to be identified without interference from translocation effects. Genetically transformed hairy roots produced by infection of plants with Agrobacterium rhizogenes are a convenient form of organ culture (Doran, 1997) and have been used previously in phytoremediation studies (Hughes et al, 1997;Macek et al, 1994;Maitani et al, 1996;Metzger et al, 1992). However, as generation of hairy roots of hyperaccumulating species has not been reported previously, their abilities to hyperaccumulate metals and their utility in hyperaccumulation research have not yet been demonstrated (Nedelkoska and Doran, 2000).…”

Ni‐induced oxidative stress in roots of the Ni hyperaccumulator, Alyssum bertolonii

“…As plant roots are in direct contact with heavy metal environments, their responses are of particular interest. Hairy root cultures have been used as an experimental tool in several studies of metal uptake by both hyperaccumulator (Nedelkoska & Doran, 2000, 2001) and nonhyperaccumulator (Metzger et al ., 1992; Maitani et al ., 1996; Macek et al ., 1997; Wu et al ., 2001) species. Previously, hairy roots of Alyssum bertolonii were shown to tolerate and hyperaccumulate Ni in the absence of shoots or leaves (Nedelkoska & Doran, 2001).…”

Hyperaccumulation of Nickel by Hairy Roots of Alyssum Species: Comparison with Whole Regenerated Plants

“…More recently, hairy roots have also been used in phytoremediation research. Transformation of xenobiotic materials such as TNT (2,4,6‐trinitrotoluene: Hughes et al, 1997) and uptake of heavy metals (Macek et al, 1994; Maitani et al, 1996; Metzger et al, 1992; Nedelkoska and Doran, 2000; Santinà di Toppi et al, 1999) have been examined using hairy root systems. Hairy roots offer important practical advantages, especially in fundamental studies of heavy metal uptake and tolerance (Nedelkoska and Doran, 2000; Pletsch et al, 1999).…”