Influence of ectomycorrhizal colonization on the growth and mineral nutrition of Populus deltoides under Aluminum toxicity

Aluminum (Al) toxicity has been considered an important factor in limiting the growth and nutrient acquisition of sensitive tree species in acidic soils. Mycorrhizal fungi may offset the negative impacts of Al in the root zone. Here, we report our studies on the effect of Al on the growth and mineral nutrition of Populus deltoides in the presence of the ectomycorrhizal fungus Paxillus involutus. Mycorrhizal and non-mycorrhizal plants were exposed to Al levels of 0, 50, 100 and 200 mg/l for 10 weeks. The biomass of mycorrhizal plants increased significantly than non-mycorrhizal plants. The mycorrhizal plants showed higher levels of mineral nutrients such as phosphorus, calcium and magnesium compared to nonmycorrhizal plants in different concentrations of Al. Al content significantly decreased in shoots of mycorrhizal plants compared to non-mycorrhizal plants. The oxalic acid concentration was significantly increased in mycorrhizal plants over non-mycorrhizal plants. These results suggest that ectomycorrhizal colonization confer Al tolerance to P. deltoides plants and Al induced enhancement of organic acids by P. involutus is very likely to be associated with Al tolerance.