Abstract
The persistent nature of lead (Pb) and cadmium (Cd) in the environment severely affects plant growth and yield. Conversely, plants acquire zinc (Zn) from the soil for their vital physiological and biochemical functions. However, the interplay and coordination between essential and toxic metals for their uptake and translocation and the putative underlying epigenetic mechanisms have not yet been investigated in maize. Here, we report that the presence of Zn facilitates the accumulation and transport of Pb and Cd in the aerial parts of the maize plants. Moreover, the Zn, Pb, and Cd interplay specifically interferes with the uptake and translocation of other divalent metals, such as calcium and magnesium. Zn, Pb, and Cd, individually and in combinations, differentially regulate the expression of DNA methyltransferases, thus alter the DNA methylation levels at the promoter of Zinc-regulated transporters, Iron-regulated transporter-like Protein (ZIP) genes to regulate their expression. Furthermore, the expression of histone deacetylases (HDACs) varies greatly in response to individual and combined metals, and HDACs expression showed a negative correlation with ZIP transporters. Our study highlights the implication of DNA methylation and histone acetylation in regulating the metal stress tolerance dynamics through Zn transporters and warns against the excessive use of Zn fertilizers in metal contaminated soils.
Highlights
Plants are exposed to diverse fluctuating environmental challenges during their development that can affect their fitness, survival and yield [1]
We found that the exposure of plants to Pb, Cd, or Zn leads to an accumulation of the respective metals into the roots, shoots, and leaves (Table 1), showing that each metal is imported into the root and transported toward the aerial parts
We found that all histone deacetylases (HDACs) respond differently to each metal
Summary
Plants are exposed to diverse fluctuating environmental challenges during their development that can affect their fitness, survival and yield [1]. Among these challenges, crop plant exposure to various heavy metals in the soil is one of the leading factors that impairs morphological, physiological, biochemical, and molecular processes in plants, contributes to the reduction of yield [1,2]. The impacts of cadmium (Cd), lead (Pb), mercury (Hg), and chromium (Cr) heavy metals on plant physiology, biochemical processes, and yield have been extensively studied in plants [3,4,5] Apart from these heavy metals, plants acquire essential metals such as iron (Fe), zinc (Zn), manganese (Mn), copper (Cu) and nickel (Ni) from the soil for their vital physiological and biochemical functions during their development [6,7]. Plants have evolved a sophisticated system to balance the uptake, storage, and utilization of these metals
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