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Small RNAs – The Big Players in Developing Salt-Resistant Plants

as salt-induced drought stress responses. Technological advancement has

also enlightened the influence of salinity stress on structural conformations,

function features and networks of the transcription factors and it is crucial

to identify the particular role of each transcription factor or gene prior to

gene modification during the creation of salt-resistant cultivar. Most of

the eukaryotic organisms adopted some small RNA-based mechanisms to

withstand unfavorable conditions (Agrawal et al., 2003). Creditable research

on various plants has identified the function of some small RNAs (sRNAs),

which significantly regulate salt tolerance responses. To date, an enormous

number of sRNAs together with their biogenesis and mechanism of action

have been recognized in many crop plants. Endogenous sRNAs, which are

linked with the genetic control of many morphological and physiological

traits in plants, are increasingly regarded as essential factors in the regulation

of salt tolerance in plants. Gene regulation is generally executed through the

condensation and transcriptional repression of chromatin, i.e., formation of

heterochromatin and it is essential for controlling gene expression in every

event of growth and development including silencing parasitic gene elements,

genome stability and inheritance (Johnson & Straight, 2017). Significant

research has established that RNA interference (RNAi) and heterochromatin

production are linked, but they were previously considered to be regulated

by entirely distinct, even unrelated processes (Martienssen & Moazed,

2015). RNA interference (RNAi) is now specifically used to refer the gene

silencing, which is executed by exogenous double-stranded RNA (dsRNA),

but in a broader sense, it refers the all the gene silencing, which is triggered

by sRNAs in combination with a representative of the Argonaute protein

family (Fire et al., 1998; Martienssen & Moazed, 2015). Comprehensive

knowledge about sRNA mediated molecular mechanisms of stress responses

would provide a thorough understanding of the initiation and progression of

stress tolerance and is essential to develop stress-resistant plants. Adequate

understanding over the last couple of decades has indicated that sRNAs are

more common than previously assumed. Ongoing and forthcoming inves­

tigations will optimistically provide more needful and detailed to combat

effectively salt-induced stress as well as other kinds of abiotic stresses.

9.2 SALINITY

Salinity is regarded as a decisive abiotic stress factor that is deleterious for

most crop plants. Globally, it causes enormous losses to crop production, and