Evaluation of fungus Piriformospora indica Effects on Some Morphophysiological Traits of Radish under Heavy Metal Stress

Piriformospora indica is an endophytic fungus, which transfers several benefits to hosts including enhance plant growth and induce tolerance to abiotic stress as heavy metals stress. The aim of this study was to investigate the effect of P. indica on some morphophysiological parameters of radish (Raphanus sativus) under normal conditions and heavy metal stress. 

This experiment was conducted as a factorial experiment in a completely randomized design with three replications in the greenhouse of Agricultural Faculty of Malayer University. The experimental factors included four heavy metals (zinc, nickel, lead and control) and three fungal inoculums (inoculated with spores and mycelium and non-inoculated). Shoot dry weight, relative water content, photosynthetic pigments, electrolyte leakage, total soluble carbohydrate, protein and proline contents were investigated parameters. 

The results showed that the heavy metal stress significantly decreased dry weight, RWC, chlorophyll, total soluble carbohydrate, protein and proline contents; whereas inoculation with fungual spore and mycelium affected parameters such as proline, total soluble carbohydrate and protein and mitigated the adverse effect of heavy metal stress. Heavy metal stress with increasing electrolyte leakage causes membrane instability, whereas inoculation with P. indica especially spore decreased lipid peroxidation. 

Using biotic methods can play an important role in counteracting with toxic effect of heavy metals. Based on these results and because P. indica can be propagated axenically on various medium, it can be concluded that this endophytic fungus serves as a promising approach to clean soil contaminated with heavy metal ions.