School of Environmental and Safety Engineering, Jiangsu Polytechnic University, Changzhou 213164, China.
J Environ Sci (China). 2010;22(7):1067-72. doi: 10.1016/s1001-0742(09)60218-7.
To understand certain mechanisms causing variations between rice cultivars with regard to cadmium uptake and tolerance, pot soil experiments were conducted with two rice cultivars of different genotypes under different soil Cd levels. The relationships between plant Cd uptake and iron/manganese (Fe/Mn) plaque formation on roots were investigated. The results showed that rice cultivars differed markedly in Cd uptake and tolerance. Under soil Cd treatments, Cd concentrations and accumulations in the cultivar Shanyou 63 (the genotype indica) were significantly higher than those in the cultivar Wuyunjing 7 (the genotype japonica) (P < 0.01, or P < 0.05), and Shanyou 63 was more sensitive to Cd toxicity than Wuyunjing 7. The differences between the rice cultivars were the largest at relatively low soil Cd level (i.e., 10 mg/kg). Fe concentrations in dithionite-citrate-bicarbonate root extracts of Shanyou 63 were generally lower than that of Wuyunjing 7, and the difference was the most significant under the treatment of 10 mg Cd/kg soil. The results indicated that the formation of iron plaque on rice roots could act as a barrier to soil Cd toxicity, and may be a "buffer" or a "reservoir" which could reduce Cd uptake into rice roots. And the plaque may contribute, to some extent, to the genotypic differences of rice cultivars in Cd uptake and tolerance.
为了理解导致不同水稻品种在镉吸收和耐受方面存在差异的某些机制，在不同土壤镉水平下，用两个不同基因型的水稻品种进行了盆栽土实验。研究了植物镉吸收与根铁/锰（Fe/Mn）斑块形成之间的关系。结果表明，不同水稻品种在镉吸收和耐受方面存在显著差异。在土壤镉处理下，籼稻品种汕优 63（基因型籼稻）的镉浓度和积累量明显高于粳稻品种武运粳 7（基因型粳稻）（P<0.01，或 P<0.05），而且汕优 63 对镉毒性更敏感。在相对较低的土壤镉水平（即 10mg/kg）下，水稻品种之间的差异最大。在 10mg/kg 土壤镉处理下，汕优 63 的二硫代丁二酸盐-柠檬酸盐-碳酸氢盐根提取物中的铁浓度普遍低于武运粳 7，差异最显著。结果表明，水稻根中铁斑的形成可以作为土壤镉毒性的屏障，并且可能是一种“缓冲”或“储库”，可以减少镉向水稻根中的吸收。而且斑块在一定程度上可能导致水稻品种在镉吸收和耐受方面存在基因型差异。
