The effect of lead treatments on seed germination and seedling mortality mediated by fungal infection in two Marrubium cuneatum ecotypes

The effect of lead treatments on seed germination and seedling mortality mediated by fungal infection in two Marrubium cuneatum ecotypes

Marrubium cuneatum is one of the endemic Iranian plant species, whose interesting ability to grow in lead-contaminated environments has not yet been evaluated. Therefore, the aim of this study was to investigate the toxicity of lead on the germination percentage as well as seedling mortality mediated by fungal infection in two M. cuneatum ecotypes. M. cuneatum plant seeds grown around Tang Dozan mine (Pb-contaminated site) and Murghab spring (non-contaminated site) were used for present study as metallicolous (M) and non-metallicolous (NM) ecotypes, respectively. Seeds were exposed to Pb treatments at concentrations of 0, 5, 10, 25, 50, 100, 150 and 200 mg / L. Germination percentage (GP) and healthy plant percentage (HPP) stimulated by low concentrations of Pb (10 and 25 mg / L) in both ecotypes, whereas inhibited at high concentrations of Pb. However, adverse effects of Pb at high concentrations on GP and HPP in M ecotype were significantly less than those of NM ecotype. In addition, seedlings death (SD) mediated by fungal infection gradually decreased with increasing Pb in both ecotypes. Considering this data, it can be concluded that M ecotype has more tolerance to lead toxicity than NM ecotype due to the adaptation caused by growth in a Pb-contaminated environment. Also, despite the toxic effects of Pb on seed germination, our data suggested that Pb treatments can moderate the seedling death (SD) mediated by fungal infection in both M. cuneatum ecotypes.