Biochemical,transcriptomic and toxicity responses of mercury-treated lowland tomato plant

Malaysia, positioned as a developing nation in Asia, confronts a pressing issue of mercury (Hg) pollution, notably in regions such as West Port, Malacca Straits, Prai, and Johor due to extensive industrial operations. This problem has far-reaching implications for food safety, evidenced by elevated Hg levels in seafood along the west coast, exceeding permissible limits in the Straits of Malacca. Moreover, the contamination extends beyond marine products, with tropical fruits in Malaysia bearing traces of Hg, a consequence linked to the utilization of agricultural inputs. The overarching challenge of Hg pollution is exacerbated by the rapid urbanization and industrialization observed in lowland areas, presenting a substantial risk to both the ecosystem and the security of food supply, including vegetables. This environmental concern is particularly detrimental to the growth and yield production of various vegetables. Addressing these interconnected issues requires a thorough comprehension of the sources, pathways, and impacts of Hg pollution, coupled with strategic interventions to safeguard public health and environmental sustainability. In this study, the biochemical and physiological responses of low land tomato plants exposed to varying concentrations of Hg (ranging from 0 to 0.25 ppm) were investigated. Furthermore, the toxicity of Hg-treated tomatoes was evaluated using zebrafish embryos (n ≥ 24). The embryos were treated with fruits extracts containing 0 to 2.5 ppb Hg, with DMSO serving as a control. There were notable differences in biochemical parameters observed across the Hg treatments in tomato plants. Plant growth exhibited a declining trend, and chlorophyll content in the leaves decreased with exposure to higher Hg concentrations. Flavonoid and phenolic levels increased in Hg-exposed leaves, fruits, and roots compared to the control-treated plants. Concurrently, proline and lipid peroxidation levels rose in the leaves, fruits, and roots of tomato plants treated with high Hg concentrations compared to the control plants. In the experiment, at an Hg concentration of 0.25 ppm, Hg accumulation was measured at 0.20 ppm in the roots, 0.006 ppm in the leaves, and 0.0002 ppm in the fruits. The total RNAs in the fruits in the control and treated fruits were 76.5 – 90.6m ng/µL. RNA-Sequencing was employed to analyze the molecular changes at transcriptome levels of the control and Hg-treated tomato ripe fruits at 0.25 ppm. Through differential gene expressions (DEGs), various genes associated with Hg intake were identified. Cupin, metallothionein, and glycosylphosphatidylinositol genes were identified as genes encoding metal-accumulating proteins in tomato fruit. Deformities and a decrease in survival and hatching rates were observed in zebrafish embryos treated with fruit extracts containing 2.5 ppb Hg. In conclusion, Hg induces its toxic effects on the growth and yield production of lowland tomatoes by altering crucial biochemical parameters and exerting toxic effects on zebrafish embryos.

Text 125085 - Full Text.pdf Download (5MB) Official URL or Download Paper: http://ethesis.upm.edu.my/id/eprint/18804

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