pre-flowering stage, a total of 633 DEGs were observed including multiple salicylic
acid, ethylene-pathway genes, PR genes, ROS genes, and WRKY TF encoding
genes (Madronero et al. 2018). In another published article, in-depth RNA-Seq
was carried out to unravel the transcriptional changes associated with the symptoms
of TYLCV and tomato chlorosis virus. Comparative analysis of DEGs for both
viruses revealed that WRKY6 levels were highly altered among the WRKY TF
family which positively regulates the crosstalk between the expressions of
phytopathogens-related as well as senescence-associated genes (Seo et al. 2018).
The in-depth promoter region analysis for Cestrum yellow leaf curling virus was
done to elucidate the interacting factors responsible for NPR1-dependent SA signaling induction which leads to synergistic identification of WRKY53 TF as a partner
(Sarkar et al. 2018).
The positive role of AtWRKY30 was confirmed in resistance against CMV using
overexpression and mutant studies in addition to oxidative stress, fungus, SA, and
ABA (Zou et al. 2016). In CGMMV-infected cucumbers, expression profiling data
confirmed both miRNA854 and miRNA5658 target WRKY21 and LRR receptor
kinase as well as FLS2-like protein which is together known in the literature to play
role in defense responses/phytopathogens resistance (Liang et al. 2019). The combinatorial effect of low light intensity/shading and Soybean mosaic virus on the
transcriptome level of soybean plants was assessed. Among all the 24 DEGs related
to plant–pathogen interaction, a total of two WRKY genes (WRKY33 and WRKY62)
were differentially expressed under both light conditions (Zhang et al. 2019a).
More recently, the effect of infection by both rice tungro viruses (Rice tungro
bacilliform virus and RTSV) at the rice transcriptomic landscape was deduced by
using global gene expression changes using Illumina Hiseq 2500 platform followed
by qRT-PCR. About 959 DEGs were related to stress-responsive pathways and
hormonal homeostasis. Among all DEGs, the reported WRKY transcription factors
were
LOC_Os05g25770,
LOC_Os08g38990,
LOC_Os09g25060,
and
LOC_Os11g02520 (Kumar and Dasgupta 2020). Taking together all these studies
at a point, we can conclude that the WRKY TFs regulate host defenses against
viruses at various levels directly or indirectly. The various methods cover direct
modulation of viral target/plant defense genes (downstream), repression as well as
activation of additional TFs through feed-forward or -backward regulation.
11.5.2 Role of Host Plant WRKY Against Bacterial Diseases
Unlike viruses, the bacteria grow in the spaces between plant cells and cause
multiple symptoms including cankers, wilts, soft rots, blights, scabs, galls, and leaf
spots (APS 2020). The change in host plant WRKY TFs levels in response to the
bacterial diseases has been reported in multiple reports of the literature. The first
report in the literature regarding the elicitor-induced nature of WRKYs in response
to bacteria was by the group of Dellagi et al. (2000). Their group first-time isolated
an upregulated potato StWRKY1 protein using the SSH technique upon inoculation
of Erwinia carotovora subsp. atroseptica culture filtrate. P. syringae pv. tomato
11 Role of WRKY Transcription Factor Superfamily in Plant Disease Management
345
acid, ethylene-pathway genes, PR genes, ROS genes, and WRKY TF encoding
genes (Madronero et al. 2018). In another published article, in-depth RNA-Seq
was carried out to unravel the transcriptional changes associated with the symptoms
of TYLCV and tomato chlorosis virus. Comparative analysis of DEGs for both
viruses revealed that WRKY6 levels were highly altered among the WRKY TF
family which positively regulates the crosstalk between the expressions of
phytopathogens-related as well as senescence-associated genes (Seo et al. 2018).
The in-depth promoter region analysis for Cestrum yellow leaf curling virus was
done to elucidate the interacting factors responsible for NPR1-dependent SA signaling induction which leads to synergistic identification of WRKY53 TF as a partner
(Sarkar et al. 2018).
The positive role of AtWRKY30 was confirmed in resistance against CMV using
overexpression and mutant studies in addition to oxidative stress, fungus, SA, and
ABA (Zou et al. 2016). In CGMMV-infected cucumbers, expression profiling data
confirmed both miRNA854 and miRNA5658 target WRKY21 and LRR receptor
kinase as well as FLS2-like protein which is together known in the literature to play
role in defense responses/phytopathogens resistance (Liang et al. 2019). The combinatorial effect of low light intensity/shading and Soybean mosaic virus on the
transcriptome level of soybean plants was assessed. Among all the 24 DEGs related
to plant–pathogen interaction, a total of two WRKY genes (WRKY33 and WRKY62)
were differentially expressed under both light conditions (Zhang et al. 2019a).
More recently, the effect of infection by both rice tungro viruses (Rice tungro
bacilliform virus and RTSV) at the rice transcriptomic landscape was deduced by
using global gene expression changes using Illumina Hiseq 2500 platform followed
by qRT-PCR. About 959 DEGs were related to stress-responsive pathways and
hormonal homeostasis. Among all DEGs, the reported WRKY transcription factors
were
LOC_Os05g25770,
LOC_Os08g38990,
LOC_Os09g25060,
and
LOC_Os11g02520 (Kumar and Dasgupta 2020). Taking together all these studies
at a point, we can conclude that the WRKY TFs regulate host defenses against
viruses at various levels directly or indirectly. The various methods cover direct
modulation of viral target/plant defense genes (downstream), repression as well as
activation of additional TFs through feed-forward or -backward regulation.
11.5.2 Role of Host Plant WRKY Against Bacterial Diseases
Unlike viruses, the bacteria grow in the spaces between plant cells and cause
multiple symptoms including cankers, wilts, soft rots, blights, scabs, galls, and leaf
spots (APS 2020). The change in host plant WRKY TFs levels in response to the
bacterial diseases has been reported in multiple reports of the literature. The first
report in the literature regarding the elicitor-induced nature of WRKYs in response
to bacteria was by the group of Dellagi et al. (2000). Their group first-time isolated
an upregulated potato StWRKY1 protein using the SSH technique upon inoculation
of Erwinia carotovora subsp. atroseptica culture filtrate. P. syringae pv. tomato
11 Role of WRKY Transcription Factor Superfamily in Plant Disease Management
345