Nickel Metal Uptake and Metal-Specific Stress Alleviation in a Perennial Desert Grass Cenchrus ciliaris

Associations of Vesicular Arbuscular Mycorrhizal Fungi (VAMF) with plant roots are known to function from Stress Alleviation to Bioremediation in metal polluted soils. We have studied uptake and accumulation of Nickel metal in a perennial grass, Cenchrus ciliaris, from Cholistan desert in the presence or the absence of mycorrhizal colonization of its roots by a fungus Glomous mosseae. Our results show that Cenchrus ciliaris has a tendency to absorb and tolerate the Nickel metal present in the contaminated soils and its shoots accumulate more Nickel than its roots. Introduction of Nickel in the plant rhizosphere generates stress that at some concentrations creates anatomical changes both at macro and microscopic levels. Such concentrations also adversely affect fungal colonization. Nature and extent of the stress directly correlate with the concentration of the Nickel metal in the soil. Metal exposure alone or in combination with the mycorrhiza produces specific changes in some enzyme activities both in the root and the shoot tissues suggesting that these changes are involved in progression/regression of the metal-specific stress. While Glomous mosseae association is not required for Nickel uptake and accumulation by Cenchrus ciliaris, it appears to be helpful in alleviating the stress exerted by the presence of this metal in soil. We conclude that the perennial desert grass Cenchrus ciliaris is capable of mobilizing and up taking Nickel metal from soil, its transportation from roots to shoots and is equipped with the machinery that helps tolerate the metal-specific stress to some extent.