Blaudez D, Botton B, Chalot M
University Henri Poincaré Nancy I, Faculty of Sciences, Laboratory of Forest Biology, UA INRA 977, P.O. Box 239, 54506 Cedex, Vandoeuvre, France
FEMS Microbiol Ecol. 2000 Jul 1;33(1):61-67. doi: 10.1111/j.1574-6941.2000.tb00727.x.
The effects of the heavy metals Cu, Cd, Ni, Pb and Zn on [(14)C]methylamine and [(14)C]aminoisobutyric acid uptake were studied in the free-living fungus Paxillus involutus and in mycorrhizal and non-mycorrhizal birch roots. The uptake of both N sources by P. involutus was inhibited by the five metals tested. However, Cu(2+) and Pb(2+) had a greater inhibitory effect. Non-competitive inhibitions were determined between heavy metals and [(14)C]methylamine uptake. [(14)C]Methylamine uptake was reduced by one third by 2 µM Cd(2+) and Cu(2+) in non-mycorrhizal roots, whereas that of mycorrhizal roots was not affected. However, it was reduced by 30 to 80% by 200 µM Cd(2+) and Cu(2+) irrespective of the mycorrhizal status. [(14)C]Aminoisobutyric acid uptake in mycorrhizal roots was not significantly affected by Cd(2+) and Cu(2+), whereas that of non-mycorrhizal roots was decreased by 77% at 200 µM Cu(2+). [(14)C]Aminoisobutyric acid uptake was 4.5 to 6 fold higher in mycorrhizal roots, compared with non-mycorrhizal roots, even under metal exposure. The high efficiency of N acquisition by mycorrhizal birch seedlings under metal exposure might be regarded as a mechanism of stress avoidance.
研究了重金属铜（Cu）、镉（Cd）、镍（Ni）、铅（Pb）和锌（Zn）对自由生活的真菌卷缘桩菇以及菌根和非菌根桦树根吸收[¹⁴C]甲胺和[¹⁴C]氨基异丁酸的影响。所测试的五种金属均抑制了卷缘桩菇对这两种氮源的吸收。然而，Cu²⁺和Pb²⁺的抑制作用更强。确定了重金属与[¹⁴C]甲胺吸收之间存在非竞争性抑制。在非菌根根中，2 μM的Cd²⁺和Cu²⁺使[¹⁴C]甲胺的吸收降低了三分之一，而菌根根的吸收不受影响。然而，无论菌根状态如何，200 μM的Cd²⁺和Cu²⁺都会使其降低30%至80%。Cd²⁺和Cu²⁺对菌根根中[¹⁴C]氨基异丁酸的吸收没有显著影响，而在200 μM Cu²⁺时，非菌根根中[¹⁴C]氨基异丁酸的吸收降低了77%。即使在金属暴露的情况下，菌根根中[¹⁴C]氨基异丁酸的吸收也比非菌根根高4.5至6倍。金属暴露条件下菌根桦树苗对氮的高效获取可能被视为一种应激规避机制。
