Cr Stable Isotope Fractionation in Arbuscular Mycorrhizal Dandelion and Cr Uptake by Extraradical Mycelium

Abstract

As common soil fungi that form symbioses with most terrestrial plants, arbuscular mycorrhizal (AM) fungi play an important role in plant adaptation to chromium (Cr) contamination. However, little information is available on the underlying mechanisms of AM symbiosis on plant Cr resistance. In this study, dandelion (Taraxacum platypecidum Diels.) was grown with and without inoculation of the AM fungus Rhizophagus irregularis and Cr uptake by extraradical mycelium (ERM) was investigated by a compartmented cultivation system using a Cr stable isotope tracer. The results indicated that AM symbiosis increased plant dry weights and P concentrations but decreased shoot Cr concentrations. Using the Cr stable isotope tracer technology, the work provided possible evidences of Cr uptake and transport by ERM, and confirmed the enhancement of root Cr stabilization by AM symbiosis. This study also indicated an enrichment of lighter Cr isotopes in shoots during Cr translocation from roots to shoots in mycorrhizal plants.

Chromium immobilization by extraradical mycelium of arbuscular mycorrhiza contributes to plant chromium tolerance

“…In order to strictly investigate direct interaction between ERM and Cr, two mycorrhizal treatmentsone without Cr(VI) addition to HC (treatment "+M À Cr") and the other with 0.45 mm acetate fiber filter (treatment "+M + F + Cr") -were included as controls in experiment II. Similar to our previous study (Chen et al, 2007a;Ren et al, 2015), the mycelium developed well in the inoculated treatments, and passed through the 37 mm nylon net to HC, while 0.45 mm acetate fiber filter excluded mycelium development in HC. Little hyphae detected in soils of the non-inoculated treatments were probably dead or saprophytic hyphae, and were also considered to be present in the inoculated treatments.…”

Chromium immobilization by extra- and intraradical fungal structures of arbuscular mycorrhizal symbioses

“…The restrain of heavy metals by plant cell walls is a common way plant relieve metal toxicity, which has also been reported in many previous studies [56][57][58][59]. The highly accumulated Cr in the intraradical fungal structures may result from Cr uptake and transport to mycorrhizal roots by the extraradical mycelium [20,21,60], or from Cr transport to the intraradical fungal structures from plant cells that take up Cr directly from the environment. Metal compartmentation by intraradical fungal structures was also reported for Cd in previous study [15].…”

The effect of Rhizophagus irregularis on salt stress tolerance of Elaeagnus angustifolia roots

“…AMF spores were separated from the soil by wet sieving and 50% sucrose centrifugation (Brundrett et al 1996). We determined hyphal length density in rhizosphere soil of E. angustifolia by Trypan blue staining (Ren et al 2015).…”