Submitted to: Abstracts for New Phytologist Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 9/30/2002
Publication Date: 9/30/2002
Citation: Interpretive Summary:
Technical Abstract: Phytoextraction will be applied only where a soil contaminant is sufficiently bioavailable or phytoavailable to require remediation. Extensive study of soil Cd risk has recently demonstrated that the high prevalence of renal tubular dysfunction in aged subsistence rice farmers in Japan and China occurred because rice grain Zn is not increased even on highly Zn contaminated soils, and because subsistence rice consumption induces Fe, Zn, and Ca malnutrition, each of which promotes Cd absorption and risk. Thus soils which will require Cd phytoextraction are very limited: rice and tobacco soils, and those contaminated with Cd but have low Zn:Cd ratio such that soil Cd is highly food-chain mobile and bioavailable. Because most plants accumulate Cd and Zn at about the same ratio found in the soil, a useful Cd phytoextraction technology must have plants which can accumulate very high amounts of Cd regardless of the presence of Zn. By 1996, we reported ecotypes of Thlaspi caerulescens which accumulate over 10-times higher Cd relative to Zn than found for the widely studied `Prayon' ecotype. Soil acidification substantially increased annual Cd phytoextraction. Examination of genetic variation for Cd accumulation by families from individual maternal plants collected in south-central France shows variation needed to breed improved cultivars of commercial utility. We are presently working to combine the Super-Cd-Accumulator and high yield traits to breed commercial Cd phytoextraction cultivars. As with our commercial Ni phytomining technology in which a new crop plant, Alyssum murale, has been domesticated, use of appropriate agronomic practices, fertilization, and chemical weed control are required.