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

Abstract

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.

Accumulation and Translocation of Phosphorus, Calcium, Magnesium, and Aluminum in Pinus massoniana Lamb. Seedlings Inoculated with Laccaria bicolor Growing in an Acidic Yellow Soil

“…In this study, all three ECM isolates showed a remarkable ability to improve the growth and Al tolerance of 16-week-old P. massoniana seedlings grown in an acidic yellow soil in the field, even under +Al treatment (Figure 1), which verified that ECM inoculation could improve Al resistance in its host. Similar results were observed for other ECM fungi, including Pisolithus tinctorius and Paxillus involutus, which could improve the Al tolerance of their host plants Eucalyptus [8], Pinus densiflora [9], Populus deltoides [11], and Picea abies [10]. Moreover, Al tolerance conferred by ECM inoculation differed among the ECM isolates, and L. bicolor S238A demonstrated the best Al resistance in P. massoniana seedlings (Figure 1).…”

“…Ectomycorrhizae could ameliorate metal toxicity, partly because these fungi could prevent plants from absorbing metals from the soil [8,11,45,46]. Results from our study provided partial support for this statement (Figure 2d).…”

“…Considering plant Ca and Mg uptake, the role of ECM fungi differed with respect to fungal species or ecotypes, host plant species, and growth conditions. For example, an Al-tolerant Pisolithus inoculum, Paxillus involutus, and Pisolithus tinctorius (strain Pt KACC) improved Ca and Mg concentration in Eucalyptus growing in acidic mine spoil [8], Populus deltoides in Melin's liquid medium containing Al [11], and Populus growing in mine tailings [38]. However, Scholl et al [6] found that ECM colonization had no significant effects on concentrations of Ca and Mg in Pinus sylvestris seedlings grown in a semi-hydroponic system with or without Al treatment, and there was even less Ca in ECM Pinus sylvestris seedlings cultured in perlite [39].…”

“…Previous studies have reported that ECM fungi can improve Al tolerance in their host plants. For example, three Pisolithus ecotypes improved Al tolerance in Eucalyptus [8], Pisolithus tinctorius alleviated Al toxicity in Pinus densiflora [9], and Paxillus involutus significantly enhanced the growth of Populus deltoides and Picea abies under Al stress [10,11]. These results indicated that some plant species could be inoculated with ECM fungi to alleviate Al toxicity when grown in acidic soils [12].…”

Laccaria bicolor Mobilizes both Labile Aluminum and Inorganic Phosphate in Rhizosphere Soil of Pinus massoniana Seedlings Field Grown in a Yellow Acidic Soil

“…Growth inhibition is an index used extensively for the assessment of Al toxicity (5,36). Numerous studies have demonstrated that various ECM fungi, including L. bicolor (25), P. tinctorius (26,31,37), and P. involutus (38), could enhance plant growth and Al tolerance in acidic culture media. P. tinctorius inoculation also enhanced P. strobus shoot but not root growth with ϩAl treatment (31).…”