Genotoxicity and Cytotoxicity Induced in Zygophyllum fabago by Low Pb Doses Depends on the Population’s Redox Plasticity

Antonio López-Orenes,Conceição Santos,María Á Ferrer,Maria Celeste Dias,Sónia Silva,Antonio A Calderón,Helena Oliveira

doi:10.3390/horticulturae7110455

Abstract

Lead (Pb) soil contamination remains a major ecological challenge. Zygophyllum fabago is a candidate for the Pb phytostabilisation of mining tailings; nevertheless, the cytogenotoxic effects of low doses of Pb on this species are still unknown. Therefore, Z. fabago seeds collected from non-mining (NM) and mining (M) areas were exposed to 0, 5 and 20 µM Pb for four weeks, after which seedling growth, Pb cytogenotoxic effects and redox status were analyzed. The data revealed that Pb did not affect seedling growth in M populations, in contrast to the NM population. Cell cycle progression delay/arrest was detected in both NM and M seedlings, mostly in the roots. DNA damage (DNAd) was induced by Pb, particularly in NM seedlings. In contrast, M populations, which showed a higher Pb content, exhibited lower levels of DNAd and protein oxidation, together with higher levels of antioxidants. Upon Pb exposure, reduced glutathione (GSH) and non-protein thiols were upregulated in shoots and were unaffected/decreased in roots from the NM population, whereas M populations maintained higher levels of flavanols and hydroxycinnamic acids in shoots and triggered GSH in roots and shoots. These differential organ-specific mechanisms seem to be a competitive strategy that allows M populations to overcome Pb toxicity, contrarily to NM, thus stressing the importance of seed provenance in phytostabilisation programs.

Highlights

Lead (Pb) continues to be a major environmental pollutant and health hazard, globally contaminating agricultural soils and water, and entering the food chain [1]
In the absence of Pb, seeds from the M populations showed different performances according to the regions of provenance, with those from Mercader showing an initial delay in germination but later reaching the values of the NM seeds (>75%) at day 18 (Table S1)
There are evident differences in some parameters between the mining and non-mining populations, even in the absence of Pb phenotypic parameters between the mining and non-mining populations, even in the stress (Table S1), which demonstrates the importance of the seed origin on the absence of Pb stress (Table S1), which demonstrates the importance of the seed phenotype

Summary

Introduction

Lead (Pb) continues to be a major environmental pollutant and health hazard, globally contaminating agricultural soils and water, and entering the food chain [1]. Pb toxicity to plants includes disturbances in nutrient uptake and photosynthesis, resulting in reduced plant growth [2]. Pb absorption is conditioned by other metals and the competition of nutrients for the same cation transporters, which assist Pb transport across plasma membranes [3,4]. Chelation and sequestration processes to avoid Pb toxicity [5], and Pb may be immobilized in the root cell wall [6] or, inside the cell, be mobilized and accumulated in the vacuole. Pb may interact with proteins and other biomolecules, as well as increase reactive oxygen species (ROS) via indirect processes, including the inhibition of enzymes (as it is a non-redox-active metal), or it may displace essential cations from binding sites, disturbing cell metabolism and function [2,7]. Pb may interact with proteins and other biomolecules, as well as increase reactive oxygen species (ROS) via indirect processes, including the inhibition of enzymes (as it is a non-redox-active metal), or it may displace essential cations from binding sites, disturbing cell metabolism and function [2,7]. 4.0/).

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