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Biology and Biotechnology of Environmental Stress Tolerance in Plants, Volume 3

induces stress responses (Hirayama & Shinozaki, 2010; Muchate et al., 2016).

To cope with the stressful situation, many plants have evolved some compli-

cated morphological, molecular, and physiological regulatory systems. For

a few decades, many researchers have utilized sRNA-based strategies to

evaluate the stress resistance capacity of crop plants. Researchers have also

screened and identified a large number of sRNAs encoded by plant genomes

which impart significant contribution in protecting plants from various biotic

and abiotic factors. To survive in adverse circumstances, plants employ

diverse genetic, transcriptomic, and proteomic strategies. The majority of

such studies have focused on Arabidopsis thaliana, Glycine max, Gossypium

raimondii, Hordeum vulgare, Medicago truncatula, Oryza sativa, Populus

sp., Saccharum sp., Triticum turgidum, Vigna unguiculata, and Zea mays

(Noman & Aqeel, 2017). Though much exhaustive research has screened

a huge number of sRNAs only a few of them have been recognized with

detailed knowledge of their biological function:

1. In most eukaryotes, sRNAs are widely known for their gene regula-

tory action. By regulating gene expression, they can regulate many

morphological and physiological events. Some of them regulate the

gene expression downwardly and others are associated with upregu-

lation of gene expression. Most of them execute such regulation by

directing DNA to guide sequence elimination and remodeling of

chromatin, whereas some of them act on RNA to guide cleavage and

translational repression (Vaucheret, 2006).

2. Some of the sRNA molecules are also known for their capacity

to silent a gene expression. Such short nucleotide sequences bind

with specialized proteins to form Protein-RNA complexes which

ultimately induce gene silencing. sRNA mediated gene silencing is

executed through one of these three processes: (i) by decreasing the

rate of transcription; (ii) by destabilization of primary transcript or

active mRNA in the cell; or (iii) by decreasing the rate of translation

(Mirlohi & He, 2016).

3. A large number of sRNAs have been identified in plants which play

vital roles in the modulation of origin and growth of several vegeta-

tive and reproductive organs, including seeds (Singh et al., 2017).

4. Because of their mobility, these compounds are ideal riboregulators

for non-cellular silencing. Non-cellular silencing can take place on a

local or systemic level. Plants get benefit from these silencing strate-

gies because these regulators can effectively reduce the harmful