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Advances in Metabolomics Research in Environmental Stress Response in Plants

acid, α-ketoglutaric acid, glycine, aspartate, serine, and other aromatic acids

was enhanced in kernels, grains, and fifth leaf of drought-stressed plants.

In another study conducted by Do et al. (2013), the amino acids (arginine,

proline, and glutamate), polyamines (spermidine, spermine, and putrescine)

and γ-aminobutyric acid were involved in the regulation of drought stress

tolerance in the leaves of 21 rice cultivars. On analyzing the leaves and roots

of Triticum aestivum via GC-MS, the levels of amino acids such as valine

and tryptophan and other metabolites, i.e., citrate, malate, and fumarate were

enhanced and reduced, respectively in the leaf and root of drought tolerant

plant (LA754). In contrast, the level of glyceric acid was enhanced in root

and reduced in leaf. The results suggested that the metabolic composition of

root and shoot respond variably on being exposed to harsh conditions and

more variation could be noted in the shoot metabolome as compared to that

of root (Kang et al., 2019). Along with this, various metabolome studies have

been conducted in plant species such as Vitis vinifera, Glycine max, Cicer

arietinum, lentils, Nicotiana tabacum, etc., which showed that drought stress

significantly alters the metabolome profile of plants (Griesser et al., 2015;

Silvente et al., 2012; Khan et al., 2019; Muscolo et al., 2015).

14.4 CONTRIBUTION OF METABOLOME STUDY IN

AMELIORATING THE EFFECTS OF SALT STRESS

Salt can easily mix with both surface and groundwater and thus presence of

excess salt in the environment is highly toxic for the growth and develop­

ment of plants. According to Velmurugan et al. (2020), around 20% (~900

million ha) of land which is estimated to be half of the total cultivable land

is contaminated with excess salt concentration. Therefore, salt toxicity is one

the major causes of concern for the total food supply of the world. Excess

salt stress negatively hampers the morphology and biochemical function of

plants. Salt stress also inhibit seed germination, photosynthetic machineries,

gaseous exchanges, and transpiration rate, as well as lower the content of

carotenoids and chlorophyll, stomatal conductance and disintegrates the

structure of photosystem (PS) II and chloroplast (Pan et al., 2020; Zhang &

Dai, 2019). Plants uptake excess salt from soil via transporters that disturbs

absorption and homeostasis of other necessary ions such as K⁺ and Ca²⁺ along

with higher deposition of Na⁺ and Cl^– ions which leads to ionic toxicity in

plant tissues (Isayenkov & Maathuis, 2019). El-Ghazail (2020) reported that

excess accumulation of Na⁺ and Cl^– ions also enhance the formation of ROS,