Effects of Zinc, Copper and Iron Oxide Nanoparticles on Induced DNA Methylation, Genomic Instability and LTR Retrotransposon Polymorphism in Wheat (Triticum aestivum L.)

Abstract

Nanomaterials with unique and diverse physico-chemical properties are used in plant science since they improve plant growth and development and offer protection against biotic and abiotic stressors. Previous studies have explored the effects of such nanomaterials on different plant mechanisms, but information about the effects of nanomaterials on induced DNA methylation, genomic instability and LTR retrotransposon polymorphism in wheat is lacking. Therefore, the present study highlights the key role of nanoparticles in DNA methylation and polymorphism in wheat by investigating the effects of ZnO, CuO and γ-Fe₃O₄ nanoparticles (NPs) on mature embryo cultures of wheat (Triticum aestivum L.). Nanoparticles were supplemented with Murashige and Skoog (MS) basal medium at normal (1X), double (2X) and triple (3X) concentrations. The findings revealed different responses to the polymorphism rate depending on the nanoparticle type and concentration. Genomic template stability (GTS) values were used to compare the changes encountered in iPBS profiles. ZnO, CuO and γ-Fe₃O₄ NPs increased the polymorphism rate and cytosine methylation compared to the positive control while reducing GTS values. Moreover, non-γ-Fe₃O₄ NPs treatments and 2X ZnO and CuO NP treatments yielded higher polymorphism percentages in both MspI- and HpaII-digested CRED-iPBS assays and were thus classified as hypermethylation when the average polymorphism percentage for MspI digestion was considered. On the other hand, the 3X concentrations of all nanoparticles decreased HpaII and MspI polymorphism percentages and were thus classified as hypomethylation. The findings revealed that MS medium supplemented with nanoparticles had epigenetic and genotoxic effects.

Keywords: DNA methylation; genomic instability; in vitro; nanoparticles; retrotransposons; wheat.

Figure 1

iPBS profiles for various experimental groups with 2391 primers in wheat. M, 100–1000 bp DNA ladder; 1, control; 2, MS medium containing 0X ZnO NPs; 3, MS medium containing 1X ZnO NPs; 4, MS medium containing 2X ZnO NPs; 5, MS medium containing 3X ZnO NPs; 6, MS medium containing 0X CuO NPs; 7, MS medium containing 1X CuO NPs; 8, MS medium containing 2X CuO NPs; 9, MS medium containing 3X CuO NPs; 10, MS medium containing 0X γ-Fe₃O₄ NPs; 11, MS medium containing 1X γ-Fe₃O₄ NPs; 12, MS medium containing 2X γ-Fe₃O₄ NPs; 13, MS medium containing 3X γ-Fe₃O₄ NPs.

Figure 2

CRED-iPBS profiles for various experimental groups with iPBS 2391 primers in wheat. M, 100–1000 bp DNA ladder; 1, control Msp I; 2, control Hpa II; 3, MS medium supplemented with 0X ZnO NPs Msp I; 4, MS medium supplemented with 0X ZnO NPs Hpa II; 5, MS medium supplemented with 1X ZnO NPs Msp I; 6, MS medium supplemented with 1X ZnO NPs Hpa II; 7, MS medium supplemented with 2X ZnO NPs Msp I; 8, MS medium supplemented with 2X ZnO NPs Hpa II; 9, MS medium supplemented with 3X ZnO NPs Msp I; 10, MS medium supplemented with 3X ZnO NPs Hpa II; 11, MS medium supplemented with 0X CuO NPs Msp I; 12, MS medium supplemented with 0X CuO NPs Hpa II; 13, MS medium supplemented with 1X CuO NPs Msp I; 14, MS medium supplemented with 1X CuO NPs Hpa II; 15, MS medium supplemented with 2X CuO NPs Msp I; 16, MS medium supplemented with 2X CuO NPs Hpa II; 17, MS medium supplemented with 3X CuO NPs Msp I; 18, MS medium supplemented with 3X CuO NPs Hpa II; 19, MS medium supplemented with 0X γ-Fe₃O₄ NPs Msp I; 20, MS medium supplemented with 0X γ-Fe₃O₄ NPs Hpa II; 21, MS medium supplemented with 1X γ-Fe3O4 NPs Msp I; 22, MS medium supplemented with 1X γ-Fe₃O₄ NPs Hpa II; 23, MS medium supplemented with 2X γ-Fe₃O₄ NPs Msp I; 24, MS medium supplemented with 2X γ-Fe₃O₄ NPs Msp I; 25, MS medium supplemented with 3X γ-Fe₃O₄ NPs Hpa II; 26, MS medium supplemented with 3X γ-Fe₃O₄ NPs Msp I.