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Advances in Metabolomics Research in Environmental Stress Response in Plants

as micronutrients that are required for survival of plants. Apart from these

elements, heavy metals such as cadmium (Cd), chromium (Cr), aluminum

(Al), lead (Pb) and mercury (Hg) are also present in soil and are taken up

by the plants. Excess accumulation of these heavy metals in plant tissues

can lead to severe toxicity and thus their translocation from soil is tightly

regulated by the plants (Farias et al., 2013; Fidalgo et al., 2013). Higher

deposition of these toxic elements in cells might lead to reduction in biomass

and chlorophyll degradation, inhibition in the uptake of water and nutrients,

hampering growth and photosynthesis, and enhancing senescence which

eventually leads to plant death. Along with hampering the growth and devel­

opment of plants, heavy metal also negatively affects the health of human

and animals. Plants growing in the contaminated metal sites uptake higher

amount of toxic metals in their tissues that ultimately enters the food chain

and eventually make humans prone to various diseases that includes various

types of cancer and dermatitis (McLaughlinetal, 1999).

To combat heavy metal stress, plants need to stabilize their protein

structure, synchronize multi-dimensional physiological and biochemical

processes, and also alter their metabolome accordingly for developing metal

stress tolerance. Jahangir et al. (2008) showed that on being exposed to heavy

metals, the level of glucosinolates and hydroxycinnamic acid was induced in

the leaves and roots of canola plants as revealed through NMR. Similar studies

were also performed in leaves and roots of Cr and Mo stressed sunflower and

soybean plants, respectively (Ibarra et al., 2019; Xu et al., 2018). The level

of fatty acid was found to be enhanced in the tissues of Cr-stressed sunflower

plants, whereas the level of other metabolites, i.e., citric acid, gluconic acid,

L-nicotine, and flavonoids/isoflavone was found to be enhanced in Mo

stressed soybean plants. In another study, Manivasagaperumal et al. (2011)

showed that the level of carbohydrate was significantly induced in the beans

treated with higher concentration of Cu and Zn. Along with above-mentioned

metabolites, the level of other metabolites such as α-tocopherol, glutathione,

proline, histidine, and phenolics was also found to be enhanced in plants in

response to heavy metal stress (Collin et al., 2008; Singh et al., 2015; Sharma

& Dietz, 2006; Kerkeb & Kramer, 2003; Diaz et al., 2001).

14.7 CONCLUSION

In this chapter, the metabolomics approach adopted by the research

community in ameliorating the negative effects of abiotic stress (drought,