Pb Transfer Preference of Arbuscular Mycorrhizal Fungus Rhizophagus irregularis in Morus alba under Different Light Intensities

Abstract

Arbuscular mycorrhizal (AM) fungi can improve the lead (Pb) tolerance of host plants and accumulate intensive Pb in mycorrhizal roots. However, the detailed contribution of AM fungal extraradical hyphae to the plants’ Pb uptake remains unknown. In this study, mulberry (Morus alba) colonized by the AM fungus (Rhizophagus irregularis) with light treatments were linked by fungal extraradical hyphae using a three-compartment system (pot test), and their differences in responding to Pb application were compared. Shading inhibited mulberry photosynthesis and the growth of mulberry. In this study, Pb application did not affect the colonization of R. irregularis when symbiosis had already formed as the root was not exposed to Pb during the colonization and formation of the AM fungal hyphae network. The R. irregularis preferred to transfer more Pb to the unshaded mulberry than to the shaded mulberry, a condition capable of providing more C supply for fungal survival than to low-light mulberry. The Pb transferred through the mycorrhizal pathway to mulberry had low mobility and might be compartmented in the root by R. irregularis until exceeding a threshold. The relatively high expressions of MaABCG16 with high Pb concentrations in plants suggest that MaABCG16 might play an important role in Pb translocation.

Effects of Arbuscular Mycorrhizal Fungi on the Growth and Root Cell Ultrastructure of Eucalyptus grandis under Cadmium Stress

“…AMF has a certain tolerance to heavy metal stress, and a high concentration of Cd stress has a certain impact on the growth and development of AMF. Thus, high concentrations of heavy metals decrease the colonization of AMF in plant roots, but such findings may differ due to a wide variety of reasons, such as the compatibility of AMF species and plants, element concentration of metal and oxidation state, and environmental conditions [ 34 , 35 ]. Our results indicated that Cd treatment (50, 150, 300 μM) significantly increased AMF colonization compared with non-Cd treatment.…”