该实验选取处于生长期的油松（Pinus tabulaeformis）幼苗，研究土壤Cu、Cd胁迫条件下，美味牛肝菌（Boletus edulis）单独接种、红绒盖牛肝菌（Xerocomus chrysenteron）与美味牛肝菌混合接种处理，对油松幼苗的生长和重金属积累分布状况的影响，探讨不同接种对油松抗性的影响。研究发现，菌根接种不仅促进寄主油松的生长发育和生物量积累，而且显著降低油松体内的重金属积累浓度，减少重金属由根部向植物茎叶部分的转运。与单一接种相比，混合接种可以更加有效地缓解重金属对寄主的生物毒性，减少土壤中重金属元素向油松体内的转运。这种优势在高浓度的重金属胁迫环境下尤为明显。该实验中，在3 mg•kg－1 Cd胁迫下，混合菌根油松的茎叶和根部Cd浓度仅为未接种对照的59.1%和70.7%，比单一菌根降低了11.3%和18.1%，而混合菌根植物的茎叶和根部生物量干重则分别为未接种对照的1.14和1.20倍，单一菌根为未接种对照的1.18和1.17倍。在400 mg•kg－1Cu胁迫下，混合菌根植物茎叶和根部的干重分别是未接种植株的1.01和 1.09倍，而混合菌根植物茎叶和根部的Cu浓度仅为未接种植株的61.8%和79.6%，比Boletus edulis 菌根植物的Cu积累浓度下降了0.7%和3.8%。
Aims Ectomycorrhiza (ECM) was generally considered to have a positive impact on the host plant exposed in contaminated soil and could enhance heavy metal tolerance. However, most researches have focused on single-ECM seedlings in experimental conditions, and the effects of mixed-ECM on the host are inadequately studied. Because woody plants are usually inoculated by mixed-ECM in natural conditions, it is essential to study the differences between single-and mixed-ECM inoculations, especially the dissimilar effects on heavy metal tolerance, which can help us better understand the mechanism of ectomycorrhiza.
Methods After a 4-week growth period, Pinus tabulaeformis seedlings inoculated by Boletus edulis and Xerocomus chrysenteronand the uninoculated control were planted in Cu and Cd contaminated soil. We measured growth and element accumulati on 12 weeks later.
Important findings Compared with the uninoculated control, ECM inoculation not only enhanced the host’s growth and biomass, but also reduced the concentration of heavy metals and their transportation from root to shoot. Seedlings inoculate d by mixed-ECM strains had higher heavy metal tolerance than those inoculated by single-ECM strain. This advantage was especially remarkable at higher concentration. Results showed that in 3 mg•kg－1 Cd contaminated soil, Cd concentrations in the shoot and root of mixed-ECM seedlings were only 59.1%and 70.7% of the control, 11.3% and 18.1% lower than single-ECM ones. However, the dry weights of mixed-ECM seedlings’ shoot and root were 1.14 and 1.20 times than the control vs. 1. 18 and 1.17 times for single-ECM. In 400 mg•kg－1Cu contaminated soil, the dry weights of mixed-ECM seedlings’ shoot and root were 1.01 and 1.09 times than the control, while the Cu concentrations in the shoot and root of mixed-ECM seedlings were only 61.8% and 79.6% of the control, 0.7% and 3.8% lower than single-ECM seedlings.