Cover illustration: Cadmium (Cd) accumulation in grains of rice (Oryza sativa L.) is a serious agricultural problem. It is known that grain Cd level varies among genotypes, but the decisive factor for this variation has not been demonstrated. Cd uptake and xylem-mediated root-to-shoot translocation have been characterized in cv. 'Habataki' (high Cd in grains; indica subspecies) and cv. 'Sasanishiki' (low Cd in grains; japonica subspecies). Moreover, root-to-shoot Cd translocation and Cd accumulation in shoots and grains have been examined in more than 70 varieties, covering the genetic diversity of cultivated rice. Results of the present study demonstrate that root-to-shoot Cd translocation is the major process determining the genotypic variation of shoot and grain Cd accumulation. Specific cultivars ('Jarjan', 'Anjana Dhan', and 'Cho-ko-koku') have also been found which show increased Cd concentrations in xylem sap and grains compared with japonica cultivars such as 'Koshihikari' and 'Nipponbare'. (Top) Brown rice of various cultivars including 'Jarjan', 'Anjana Dhan', 'Cho-ko-koku', and 'Koshihikari'. (Bottom) The heading panicle of 'Nipponbare'. (Background) 'Nipponbare' at the grain ripening stage. Photographs and layout by S Uraguchi and S Ishikawa. (See Uraguchi et al., pp. 2677-2688.)
[Table of Contents]