Hasselt University, Centre for Environmental Sciences, Environmental Biology Group, Agoralaan, Gebouw D, 3590 Diepenbeek, Belgium.
Environ Microbiol. 2010 Aug;12(8):2133-41. doi: 10.1111/j.1462-2920.2009.02082.x. Epub 2009 Oct 14.
Adaptive Zn and Cd tolerance have evolved in populations of the ectomycorrhizal fungus Suillus luteus. When exposed to high concentrations of both metals in vitro, a one-sided antagonism was apparent in the Zn- and Cd-tolerant isolates. Addition of high Zn concentrations restored growth of Cd-stressed isolates, but not vice versa. The antagonistic effect was not detected in a S. luteus isolate from non-contaminated land and in Paxillus involutus. The fungi were inoculated on pine seedlings and subsequently exposed to ecologically relevant Zn and Cd concentrations in single and mixed treatments. The applied doses severely reduced nutrient acquisition of non-mycorrhizal pines and pines inoculated with metal-sensitive S. luteus. Highest translocation of Zn and Cd to shoots occurred in the same plants. Seedlings inoculated with fungi collected from the polluted site reduced metal transfer to their host and maintained nutrient acquisition under high metal exposure. The isolate showing highest tolerance in vitro also offered best protection in symbiosis. The antagonistic effect of high Zn on Cd toxicity was confirmed in the plant experiment. The results indicate that a Zn- and Cd-polluted soil has selected ectomycorrhizal fungi that are able to survive and protect their phytobiont from nutrient starvation and excessive metal uptake.
具有锌和镉耐性的外生菌根真菌苏力菌种群已经进化。当在体外暴露于高浓度的这两种金属时，在锌和镉耐性分离株中明显存在单方面的拮抗作用。添加高浓度的锌可以恢复镉胁迫分离株的生长，但反之则不行。在来自未污染土地的苏力菌分离株和离褶伞属中未检测到拮抗作用。将真菌接种到松树苗上，然后在单一和混合处理中暴露于生态相关的锌和镉浓度下。施加的剂量严重降低了非菌根松树和接种了对金属敏感的苏力菌的松树的养分吸收。在同一植物中，锌和镉向地上部的最大转移量最高。从污染地点采集的真菌接种的幼苗减少了金属向其宿主的转移，并在高金属暴露下维持了养分吸收。在体外表现出最高耐性的分离株在共生中也提供了最佳的保护。在植物实验中证实了高锌对镉毒性的拮抗作用。结果表明，锌和镉污染的土壤已经选择了能够生存并保护其植物共生体免受营养饥饿和过量金属吸收的外生菌根真菌。
