Department of Botany and Biochemistry, Westfield College (University of London), Kidderpore Avenue, NW3 7ST, London, UK.
Planta. 1976 Jan;132(3):209-14. doi: 10.1007/BF00399719.
Potassium chromate is more toxic to the growth of barley in solution culture than chromic chloride, though apparent uptake of the latter is much faster. Inhibitor studies indicate that CrO4 (2-) uptake is "active" whereas Cr(3+) uptake is passive, demonstrating that the two forms do not share a common uptake mechanism. Studies on the form of Cr inside root cells show that in plants fed CrO4 (2-) the Cr remains largely unchanged whereas in plants fed Cr(3+) a little CrO4 (2-) (0.5 per cent) is produced. This conversion is dependent on the presence of living material and is probably enzymatic. Chromate uptake follows Michaelis-Menten kinetics at low concentration and is competitively inhibited by sulphate. Transport of chromium up the root is very slow, accounting for the low levels of Cr in the shoots. Chromate is transported better than Cr(3+) though still to a very limited extent. These experiments provide a physiological basis for previous observations.
重铬酸钾在溶液培养中对大麦生长的毒性比氯化铬大，尽管后者的表观吸收速度快得多。抑制剂研究表明，CrO4(2-)的吸收是“主动的”，而 Cr(3+)的吸收是被动的，这表明这两种形式不共享共同的吸收机制。对根细胞内铬形态的研究表明，在喂食 CrO4(2-)的植物中，铬基本上保持不变，而在喂食 Cr(3+)的植物中，会产生少量的 CrO4(2-)（0.5%）。这种转化依赖于活物质的存在，可能是酶促的。在低浓度下，铬酸盐的吸收遵循米氏动力学，并且被硫酸盐竞争性抑制。铬在根部的向上运输非常缓慢，导致地上部分的 Cr 含量很低。尽管铬酸盐的运输情况比 Cr(3+)好，但仍然非常有限。这些实验为以前的观察结果提供了生理学基础。
