Effect of Mycorrhizal Fungus on the Expressions of NRAMP1 Transporter in Medicago sativa under Cadmium Stress

Cadmium (Cd) is one of the most phytotoxic elements causing an agricultural problem and human health harmful. Inoculation of arbuscular mycorrhiza (AM) is a potential tool for increasing the tolerance of plants to stress conditions in soils contaminated with heavy metals. The family of NRAMP metal ion transporters could participate in Cd uptake or transport in alfalfa (Medicago sativa L). Expression analysis of MsNRAMP1 was performed by quantitative qRT-PCR (reverse transcription PCR) in roots of 5-week-old plants inoculated with Rhizophagies irregular under Cd stress. As well as, the concentration of adsorbed cadmium in plant tissues was measured by atomic absorption device. The results showed that NRAMP1 gene was significantly down regulated in the root of mycorrhizal plants under Cd treatment compared with non-mycorrhizal plant. Furthermore, accumulation of Cd was significantly higher (P<0.01) in roots of plants inoculated wit mycorrhiza than non-inoculated plants. In contrast, Cd contents in leaves of inoculated plants were decreased compared with non-AM plants. It seems that the mycorrhiza fungus did not allow the transfer of metal to the shoot through immobilization of Cd in soils, thereby reducing the toxicity of heavy metal in the plant. Consequently, Mycorrhiza can be used as an effective strategy to minimize Cd uptake in M. sativa.

Keywords:

Medicago sativa , Cadmium , Mycorrhizal Fungus , NRAMP1