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

of stress-related genes, which can include activating or deactivating them.

Reconstruction of the involved gene network and identification of key genes

involved in drought stress in barley were performed using microarray data

analysis. Finally, genes involved in response to drought stress were identified

based on analysis of related microarray experimental data, protein interac­

tion networks were reconstructed, and Hub genes were identified, including

transcription factors and HYH and HY5, DREB2A, DREB1A, ABF3, ARF1,

ABI1, and PP2CA phosphatase proteins (Javadi et al., 2017).

Drought stress tolerance, as a complex trait, includes a set of changes

including physiological, morphological, and biochemical changes at the

plant level (Zhang, 2007). Extensive studies have been performed on all plant

species to identify drought stress response genes (Tran et al., 2010). In rice,

drought-responsive genes were identified using expression profiles such as

microarrays, Expression Sequence Tags (ESTs), RNA gel blot, and qRT-PCR

(Degenkolbe et al., 2009). However, a collection of genes responding to

drought stress, especially those genes that have significant expression

changes compared to normal conditions, is essential to the performance of

the set of these genes in drought tolerance (Hruz et al., 2008).

In drought stress, ABA reduces the concentration of potassium in the

protective cells of the stomata, leading to the closure of the stomata, which

reduces water loss from the guard cells. The expression of many genes

induced by drought stress has been identified through microarray whose

products increase stress tolerance and regulate the expression of other

genes through signaling pathways. Most of these genes are associated with

increased levels of ABA in plants (Raghavendra et al., 2010). The ABI3/VP1

protein family has been reported to help ABA to increase grain filling and

stress resistance (Kermode, 2005). Application and analysis of microarray

results in Arabidopsis mutants showed that 73% of genes were affected by

VP1 and ABA, indicating a close relationship between ABA signaling and

VP1 function (Suzuki et al., 2003).

Under non-stress conditions, Reactive oxygen species (ROS) are present

in small and controlled amounts in plant cells (Dumont & Rivoal, 2019).

Stress increases the production of ROS, which are toxic and cause severe

damage to cellular components. In order to inhibit and collect oxygen free

radicals, plants produce various enzymatic and non-enzymatic antioxidants

in their cells (Sharm et al., 2012). Antioxidant enzymes include superoxide

dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), ascorbate

peroxidase (APX), monodehydroascorbate reductase (MDHAR) and dehy­

droascorbate reductase (DHAR) (Alscher et al., 2002). Using microarray