Natural Fungal Endophytes From Noccaea caerulescens Mediate Neutral to Positive Effects on Plant Biomass, Mineral Nutrition and Zn Phytoextraction

Phytoextraction using hyperaccumulating plants is a method for the remediation of soils contaminated with trace elements (TEs). As a strategy for improvement, the concept of fungal-assisted phytoextraction has emerged in the last decade. However, the role played by fungal endophytes of hyperaccumulating plants in phytoextraction is poorly studied. Here, fungal endophytes isolated from calamine or non-metalliferous populations of the Cd/Zn hyperaccumulator Noccaea caerulescens were tested for their growth promotion abilities affecting the host plant. Plants were inoculated with seven different isolates and grown for 2 months in trace element (TE)-contaminated soil. The outcomes of the interactions between N. caerulescens and its native strains ranged from neutral to beneficial. Among the strains, Alternaria thlaspis and Metapochonia rubescens, respectively, isolated from the roots of a non-metallicolous and a calamine population of N. caerulescens, respectively, exhibited the most promising abilities to enhance the Zn phytoextraction potential of N. caerulescens related to a significant increase of the plant biomass. These strains significantly increased the root elemental composition, particularly in the case of K, P, and S, suggesting an improvement of the plant nutrition. Results obtained in this study provide new insights into the relevance of microbial-assisted phytoextraction approaches in the case of hyperaccumulating plants.

Ecophysiology of nickel hyperaccumulating plants from South Africa – from ultramafic soil and mycorrhiza to plants and insects

Ecophysiological model “ultramafic soil – mycorrhiza – hyperaccumulating plants – specialised insects and other organisms” is presented for South African nickel hyperaccumulating plants.

Insight into the Phytoremediation Capability of Brassica juncea (v. Malopolska): Metal Accumulation and Antioxidant Enzyme Activity

Metal hyperaccumulating plants should have extremely efficient defense mechanisms, enabling growth and development in a polluted environment. Brassica species are known to display hyperaccumulation capability. Brassica juncea (Indiana mustard) v. Malopolska plants were exposed to trace elements, i.e., cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn), at a concentration of 50 μM and were then harvested after 96 h for analysis. We observed a high index of tolerance (IT), higher than 90%, for all B. juncea plants treated with the four metals, and we showed that Cd, Cu, Pb, and Zn accumulation was higher in the above-ground parts than in the roots. We estimated the metal effects on the generation of reactive oxygen species (ROS) and the levels of protein oxidation, as well as on the activity and gene expression of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX). The obtained results indicate that organo-specific ROS generation was higher in plants exposed to essential metal elements (i.e., Cu and Zn), compared with non-essential ones (i.e., Cd and Pb), in conjunction with SOD, CAT, and APX activity and expression at the level of encoding mRNAs and existing proteins. In addition to the potential usefulness of B. juncea in the phytoremediation process, the data provide important information concerning plant response to the presence of trace metals.

Insight into Phytoremediation Capability of Brassica juncea (v. Malopolska): Metal Accumulation and Antioxidant Enzymes Activity

Metal hyperaccumulating plants should have extremely efficient defence mechanisms, enabling growth and development in a polluted environment. Brassica species are known to display hyperaccumulation capability. Brassica juncea (Indiana mustard) v. Malopolska plants were exposed to trace elements, i.e., cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn), at a concentration of 50 M and were then harvested after 96 hours for analysis. We observed a high index of tolerance (IT), higher than 90%, for all B. juncea plants treated with the four metals, and we showed that Cd, Cu, Pb and Zn accumulation was higher in the above-ground parts than in the roots. We estimated the metal effects on the generation of reactive oxygen species (ROS) and the levels of protein oxidation as well as on the activity and gene expression of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). The obtained results indicate that organo-specific ROS generation was higher in plants exposed to essential metal elements (i.e., Cu and Zn), compared with non-essential ones (i.e., Cd and Pb), in conjunction with SOD, CAT and APX activity and expression at the level of encoding mRNAs and existing proteins. In addition to the potential usefulness of B. juncea in the phytoremediation process, the data provide important information concerning plant response to the presence of trace metals.

Effects of Two Cadmium Hyperaccumulating Plants (N. Caerulescens And A. Halleri) in Feed on Tissue Burden in Laboratory Rats

The aim of this work was to determine how two cadmium (Cd) hyperaccumulating plants in feed affect a consumer organism (Rattus norvegicus var. alba). Using inductively coupled plasma optical emission spectrometry (ICP-OES), Cd concentrations were analyzed in Wistar rat (Rattus norvegicus var. alba) tissues. Rats were fed the Cd and Zn hyperaccumulating plants Noccaea caerulescens or Arabidopsis halleri. Rats given Arabidopsis halleri took in 4 times as much Cd as did rats fed Noccaea caerulescens. However, the muscle, intestinal, kidney, spleen, testicular, bone and liver tissues of rats fed A.halleri had 7.3, 5.6, 5.5, 3.5, 3.1, 2.5 and 2.3 times higher Cd concentrations, respectively, than did tissues of rats fed N. caerulescens. A. halleri burdened the muscle, small intestinal, and kidney tissues with Cd to a greater extent than did N. caerulescens. However, the spleen, testes, bone and liver were significantly more burdened with Cd by N. caerulescens. In both experimental groups (rats given N. caerulescens as well as those given A. halleri), the highest Cd concentrations were found (in descending order) in the kidneys > liver > small intestine > spleen > testes > bone > and muscle. This information is vital in situations where, for example, livestock can graze on these plants or when other animals and humans accidentally consume these plants.