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

In a recent research study on the plant Brassica juncea, 11 recognized and

unique miRNAs were found under Cd stress-responsive miRNAs and tran­

scripts. Among this bra-miR172b-3p target for ATCCS (copper chaperone

for superoxide dismutase) and bra-miR398-3p target for FLA9 (Fasciclin-

Like Arabinogalactan-protein 9) were two of the target miRNAs that were

↓ in Cd-exposed foliages the putative Cd-specific resistance inhibitor

bra-miR172b-3p was identified to be adversely controlled in ATCCS in

response to Cd stress. These results will aid in a deeper comprehension of

the Cd-induced miRNA modulatory circuits of mustard (Liu et al., 2021).

12.2.5 SUBMERGENCE/FLOODING STRESS

The impacts of global warming have led to severe drought in several parts

of the planet, whereas the unforeseen occurrence of floods has been a catas­

trophe in different corners of the globe. As per the Food and Agriculture

Organization (FAO) of the United Nations, floods caused roughly US $19

billion in damages in developing world agriculture from 2005 to 2015.

Depending on the flooding scenario, adverse impacts may vary, affecting

mainly the roots (waterlogging) else whole plant (part or total plant drown)

(Sasidharan et al., 2017). Submergence generates a large number of chal­

lenges, including nutritional deprivation, hypoxia, infection, and low light,

all of that impede plant’s enlargement, differentiation including productivity.

Gaseous exchange in the soil is subsequently hampered under waterlogging

conditions. As a result, there is a large loss of oxygen (O2) and accumula­

tion of carbon dioxide (CO2) due to microorganisms and root respiration

(Bailey-Serres & Voesenek, 2008). Flooding enhances the development

of many pathogens which causes plant disease (Gravot et al., 2016). This

deleterious effect may be prevented by Hypoxia-triggered gene expression

by which many proteins are synthesized and that enhance the plant immunity

(Hsu et al., 2013). Hypoxia is characterized by a reduction in the amount of

oxygen surrounding a plant’s roots; its complete absence (anoxia) causes

significant ecological stress. Hypoxia prompts the roots to switch between

oxygen-requiring to non-oxygen requiring metabolic-process, resulting

in substantial limits on ATP synthesis (Barrett-Lennard, 2003; Teakle et

al., 2006). Submergence-responsive genes such as ADH1 and PDC1 have

enhanced expression in rice. Expression of the Oryza sativa ADH1 and PDC1

genes was enhanced under submergence conditions, as evidenced by higher

recruitment of RNA polII on the gene loci. The H3K4 residue in the 5’- and