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Advances in Metabolomics Research in Environmental Stress Response in Plants

Environmental stress restricts the growth and development of plants that

ultimately affects the quality and quantity of major food crops worldwide.

According to Thakur et al. (2010), abiotic factors such as drought, salinity,

heavy metal stress and extreme temperature influence the survival rate,

biomass, and crop yield of staple food crops by up to 70% which is going

to be an important cause of concern for the continuous growing population

of the world. Thus, environmental stress can be defined as any change in

surrounding factors that negatively affects the growth and development

of plants along with alteration in the metabolic profile of plants. Abiotic

stresses induce the formation of reactive oxygen and nitrogen species (ROS

and RNS) in cells that eventually cause damage to various biomolecules

like protein, carbohydrate, lipid, and DNA (Singh et al., 2020). Additionally,

excess formation of ROS can also alter the gene expression levels that hamper

the normal homeostasis of plants. To scavenge such cytotoxic metabolites,

plants produce a large number of protective metabolites. Primary metabo­

lites are involved in the biosynthesis of sugars, amino acids and lipids that

ultimately control the glycolysis and tricarboxylic acid cycle in plants which

results in the generation of ATP that fulfill the energy requirement of plants,

positively regulate the growth and development of plants, and also enhance

their survival capability on being exposed to stressed environmental condi­

tions. Additionally, primary metabolites also contribute towards the forma­

tion of secondary metabolites such as flavonoids, carotenoids, anthocyanins,

atropine, and phytic acids. Secondary metabolites do not play any critical

role in the development of plants; however, their role in reducing the nega­

tive effects of abiotic stress in plants by scavenging the ROS in plant tissues

is widely studied (Dawid & Hille, 2018). According to Razzaq et al. (2019),

some specialized secondary metabolites formed in plants are alkaloids

(~21,000), phenolics (~10,000) and terpenoids (>25,000) that enhance the

tolerance capability of plants against both abiotic and biotic stress.

In the past, various methods and research knowledge have been applied

for identification and detection of both primary and secondary metabolites

formed in plants; however, massive production, diverse chemical struc­

tures and complex nature of metabolites are the major challenges faced

by metabolomics tools during identification of whole metabolome profile

(Wishart, 2011). According to Piasecka et al. (2019), advanced techniques

for deciphering the complete metabolome profile of any plant species is still

in the non-trivial phase and a combination of various techniques comprising

of metabolite extraction and various tools for analysis of metabolites are

most often used. Additionally, integration of metabolomics with other