to provide resistance against blast pathogen. In another study, the cotton GhWRKY44
was isolated, characterized, localized, and constitutively overexpressed in
N. benthamiana. The overexpression plants exhibited enhanced resistance to
R. solani as compared with the wild-type plants. The resistance increased importantly due to the upregulation of several defense-related genes belonging to PR- and
SA-signaling (Li et al. 2015).
In the next year, i.e., 2016, another poplar PtrWRKY89 was characterized as a
transcription activator in the nucleus for increasing the susceptibility to bacteria
P. syringae as well as fungus B. cinerea as compared to the wild-type plants using
constitutive overexpression (Jiang et al. 2016). In contrast, Jiang and colleagues
overexpressed BoWRKY6 in the broccoli plants and reported enhanced downy
mildew resistance (Jiang et al. 2016). In another published article, conidial suspension of B. cinerea (strain BCT 314) inoculated in 10-week-old OE GhWRKY25
tobacco lines resulted in enhanced sensitivity by downregulating the SA- as well as
ET-signaling related genes. Their paper indicated that this GhWRKY25 plays a
negative role in response to fungal pathogen resistance (Liu et al. 2016a, 2016b).
Recently, Lui and colleagues from Nanjing Agricultural University (China)
classified various WRKY family members into three main groups based on the
conserved domains structure, collinearity, exon–intron structures, and duplications.
Furthermore, they illustrated the expression pattern of MdWRKY-encoding genes in
response to A. alternate (Lui et al. 2017). Expression profiling of apple (Cv. Golden
Delicious) infected with leaf spot fungus (A. alternata f. sp. mali.) confirmed that
both Md-miR156ab and MdmiR395 target MdWRKYN1 and MdWRKY26, respectively, and regulate resistance against the pathogen (Zhang et al. 2017). Genomewide identification and expression analysis of the WRKY TF family in
Moniliophthora perniciosa infected cacoa (Theobroma cacao) revealed that
Tc01_p014750, Tc04_p016130, Tc06_p013130, Tc06_p004420, Tc09_p001530,
and Tc10_p016570 have shown promising changes in their transcript levels (de
Almeida et al. 2017). In another published report, TaWRKY49 and TaWRKY62
silencing in wheat (Cv. Xiaoyan6) lead to a change in resistance against
P. striiformis f. sp. tritici (Wang et al. 2017). In another published article, grape
VlWRKY48 overexpression A. thaliana lines showed the enhanced disease resistance
against Golovinomyces cichoracearum as well as drought conditions in comparison
to the control-plants (Zhao et al. 2018). The reason for the enhancement was the
increased defense-related genes expression. Similarly, the melon (Cucumis melo)
showed upregulation of CmWRKY6, CmWRKY19, and CmWRKY48 even up to
sevenfold after powdery mildew fungus infection (Jiao et al. 2018). Aamir and
colleagues investigated the differential tissue-specific expression of WRKY genes
in tomato plants after challenging F. oxysporum f. sp. lycopersici. Their qRT-PCR
work revealed that SlWRKY4, SlWRKY33, and SlWRKY37 showed a clear-cut
difference (even up to fivefold) in gene expression in both leaf and root tissues.
Besides, they also showed that the SlWRKY33 interact with other proteins such as
WRKY1, WRKY40, WRKY70, MAPK5, and SIB1 (Aamir et al. 2018).
Recently, Dong et al. (2019) studied the transcriptome level changes in soybean
upon inoculation with the causal organism of soybean downy mildew, Peronospora
11 Role of WRKY Transcription Factor Superfamily in Plant Disease Management
351
was isolated, characterized, localized, and constitutively overexpressed in
N. benthamiana. The overexpression plants exhibited enhanced resistance to
R. solani as compared with the wild-type plants. The resistance increased importantly due to the upregulation of several defense-related genes belonging to PR- and
SA-signaling (Li et al. 2015).
In the next year, i.e., 2016, another poplar PtrWRKY89 was characterized as a
transcription activator in the nucleus for increasing the susceptibility to bacteria
P. syringae as well as fungus B. cinerea as compared to the wild-type plants using
constitutive overexpression (Jiang et al. 2016). In contrast, Jiang and colleagues
overexpressed BoWRKY6 in the broccoli plants and reported enhanced downy
mildew resistance (Jiang et al. 2016). In another published article, conidial suspension of B. cinerea (strain BCT 314) inoculated in 10-week-old OE GhWRKY25
tobacco lines resulted in enhanced sensitivity by downregulating the SA- as well as
ET-signaling related genes. Their paper indicated that this GhWRKY25 plays a
negative role in response to fungal pathogen resistance (Liu et al. 2016a, 2016b).
Recently, Lui and colleagues from Nanjing Agricultural University (China)
classified various WRKY family members into three main groups based on the
conserved domains structure, collinearity, exon–intron structures, and duplications.
Furthermore, they illustrated the expression pattern of MdWRKY-encoding genes in
response to A. alternate (Lui et al. 2017). Expression profiling of apple (Cv. Golden
Delicious) infected with leaf spot fungus (A. alternata f. sp. mali.) confirmed that
both Md-miR156ab and MdmiR395 target MdWRKYN1 and MdWRKY26, respectively, and regulate resistance against the pathogen (Zhang et al. 2017). Genomewide identification and expression analysis of the WRKY TF family in
Moniliophthora perniciosa infected cacoa (Theobroma cacao) revealed that
Tc01_p014750, Tc04_p016130, Tc06_p013130, Tc06_p004420, Tc09_p001530,
and Tc10_p016570 have shown promising changes in their transcript levels (de
Almeida et al. 2017). In another published report, TaWRKY49 and TaWRKY62
silencing in wheat (Cv. Xiaoyan6) lead to a change in resistance against
P. striiformis f. sp. tritici (Wang et al. 2017). In another published article, grape
VlWRKY48 overexpression A. thaliana lines showed the enhanced disease resistance
against Golovinomyces cichoracearum as well as drought conditions in comparison
to the control-plants (Zhao et al. 2018). The reason for the enhancement was the
increased defense-related genes expression. Similarly, the melon (Cucumis melo)
showed upregulation of CmWRKY6, CmWRKY19, and CmWRKY48 even up to
sevenfold after powdery mildew fungus infection (Jiao et al. 2018). Aamir and
colleagues investigated the differential tissue-specific expression of WRKY genes
in tomato plants after challenging F. oxysporum f. sp. lycopersici. Their qRT-PCR
work revealed that SlWRKY4, SlWRKY33, and SlWRKY37 showed a clear-cut
difference (even up to fivefold) in gene expression in both leaf and root tissues.
Besides, they also showed that the SlWRKY33 interact with other proteins such as
WRKY1, WRKY40, WRKY70, MAPK5, and SIB1 (Aamir et al. 2018).
Recently, Dong et al. (2019) studied the transcriptome level changes in soybean
upon inoculation with the causal organism of soybean downy mildew, Peronospora
11 Role of WRKY Transcription Factor Superfamily in Plant Disease Management
351