T-DNA insertion mutants and gain-of-function mutants (Lai et al. 2008). Similarly,
the constitutive overexpression of rice blast-induced OsWRKY31 in Japanese rice
cultivar, namely Zhonghua 17 leads to enhanced shoot length, root length, and
resistance against two blast fungus strain P131 and MS220 of M. oryzae (Zhang
et al. 2008). Levee and colleagues isolated a poplar PtWRKY23, an AtWRKY23
ortholog primarily. Later, they examined the response of PtWRKY23-misexpressing
plants for resistance to Melampsora rust using histological techniques, qRT-PCR,
and Affymetrix GeneChip. The data revealed the role of PtWRKY23 in resistance,
redox homeostasis as well as cell wall-related metabolism (Levee et al. 2009).
Similarly, the role of OsWRKY45 in multiple stresses such as salt, osmotic, drought,
cold, fungus (M. oryzae Cav.), and bacteria (X. oryzae pv. oryzae and P. syringae)
was established using various physiological parameters, gain- and loss-of-function
studies (Qiu and Yu 2009). Yang et al. (2009) studied the expression of a total of
46 WRKY TFs encoding genes in the canola infected with two devastating fungal
pathogens, namely Sclerotinia sclerotiorum and A. brassicae using quantitative real
time-PCR (qRT-PCR). Their study revealed that about 13 BnWRKYs transcript
abundance changed significantly following the fungal challenge. In another instance,
using the same protocol by Fernandez et al. (2004), 6-month-old C. arabica plants
(Var. Caturra and Tupi) were challenged with two different coffee rust (H. vastatrix)
isolates. In comparison, the second isolate elicited more number of WRKY TFs
(from twofold to sevenfold) (Ramiro et al. 2010).
The role of GhWRKY3 upon infection with mighty fungi such as Fusarium
oxysporum f. sp. vasinfectum, Colletotrichum gossypii, and Rhizoctonia solani was
elucidated (Guo et al. 2011). Fan et al. (2011) confirmed the positive role of nuclearencoded Chinese “Qinguan” apple in resistance against A. alternata f. sp. mali.
Furthermore, the MdWRKY1 overexpression tobacco plants showed enhanced resistance against the deadly oomycete, P. parasitica var. nicotianae. Similarly, the
constitutive TaWRKY45 overexpression lines also elicited the resistance against
three fungal pathogens such as F. graminearum, B. graminis, and Puccinia triticina
(Bahrini et al. 2011). Overexpression of nuclear-localized OsWRKY30 gene in rice
plants depicted the enhanced R. solani and M. grisea resistance. This occurred due to
the activated expression of JA- and PR- synthesis-related genes (Peng et al. 2012).
The similar role of OsWRKY2 (Abbruscato et al. 2012), OsWRKY45 (Shimono et al.
2012), ClWRKY70 (Cho et al. 2012), GbWRKY1 (Shu-Ling et al. 2012), OsWRKY28
(Chujo et al. 2013), OsWRKY76 (Yokotani et al. 2013), AtWRKY28 (Chen et al.
2013a), AtWRK75 (Chen et al. 2013c), GhWRKY39-1 (Shi et al. 2014a) GhWRKY39
(Shi et al. 2014b) was also elucidated against fungal pathogens such as M. grisea,
M. oryzae, S. sclerotiorum, Cladosporium cucumerinum, R. solani, and Verticillium
dahlia.
In the year 2015, an SA pathway-inducible poplar PtrWRKY73 was isolated,
characterized, and overexpressed in A. thaliana to increase the resistance against
B. cinerea (Duan et al. 2015). Similarly, Cheng et al. (2015) clarified the interrelationship between various OsWRKYs in the rice blast resistance using gain- and
loss-of-function studies. Their data revealed that OsWRKY13, WRKY42, and
WRKY45-2 interact with each other in a sequential transcriptional regulatory cascade
350
L. S. Rajput et al.
the constitutive overexpression of rice blast-induced OsWRKY31 in Japanese rice
cultivar, namely Zhonghua 17 leads to enhanced shoot length, root length, and
resistance against two blast fungus strain P131 and MS220 of M. oryzae (Zhang
et al. 2008). Levee and colleagues isolated a poplar PtWRKY23, an AtWRKY23
ortholog primarily. Later, they examined the response of PtWRKY23-misexpressing
plants for resistance to Melampsora rust using histological techniques, qRT-PCR,
and Affymetrix GeneChip. The data revealed the role of PtWRKY23 in resistance,
redox homeostasis as well as cell wall-related metabolism (Levee et al. 2009).
Similarly, the role of OsWRKY45 in multiple stresses such as salt, osmotic, drought,
cold, fungus (M. oryzae Cav.), and bacteria (X. oryzae pv. oryzae and P. syringae)
was established using various physiological parameters, gain- and loss-of-function
studies (Qiu and Yu 2009). Yang et al. (2009) studied the expression of a total of
46 WRKY TFs encoding genes in the canola infected with two devastating fungal
pathogens, namely Sclerotinia sclerotiorum and A. brassicae using quantitative real
time-PCR (qRT-PCR). Their study revealed that about 13 BnWRKYs transcript
abundance changed significantly following the fungal challenge. In another instance,
using the same protocol by Fernandez et al. (2004), 6-month-old C. arabica plants
(Var. Caturra and Tupi) were challenged with two different coffee rust (H. vastatrix)
isolates. In comparison, the second isolate elicited more number of WRKY TFs
(from twofold to sevenfold) (Ramiro et al. 2010).
The role of GhWRKY3 upon infection with mighty fungi such as Fusarium
oxysporum f. sp. vasinfectum, Colletotrichum gossypii, and Rhizoctonia solani was
elucidated (Guo et al. 2011). Fan et al. (2011) confirmed the positive role of nuclearencoded Chinese “Qinguan” apple in resistance against A. alternata f. sp. mali.
Furthermore, the MdWRKY1 overexpression tobacco plants showed enhanced resistance against the deadly oomycete, P. parasitica var. nicotianae. Similarly, the
constitutive TaWRKY45 overexpression lines also elicited the resistance against
three fungal pathogens such as F. graminearum, B. graminis, and Puccinia triticina
(Bahrini et al. 2011). Overexpression of nuclear-localized OsWRKY30 gene in rice
plants depicted the enhanced R. solani and M. grisea resistance. This occurred due to
the activated expression of JA- and PR- synthesis-related genes (Peng et al. 2012).
The similar role of OsWRKY2 (Abbruscato et al. 2012), OsWRKY45 (Shimono et al.
2012), ClWRKY70 (Cho et al. 2012), GbWRKY1 (Shu-Ling et al. 2012), OsWRKY28
(Chujo et al. 2013), OsWRKY76 (Yokotani et al. 2013), AtWRKY28 (Chen et al.
2013a), AtWRK75 (Chen et al. 2013c), GhWRKY39-1 (Shi et al. 2014a) GhWRKY39
(Shi et al. 2014b) was also elucidated against fungal pathogens such as M. grisea,
M. oryzae, S. sclerotiorum, Cladosporium cucumerinum, R. solani, and Verticillium
dahlia.
In the year 2015, an SA pathway-inducible poplar PtrWRKY73 was isolated,
characterized, and overexpressed in A. thaliana to increase the resistance against
B. cinerea (Duan et al. 2015). Similarly, Cheng et al. (2015) clarified the interrelationship between various OsWRKYs in the rice blast resistance using gain- and
loss-of-function studies. Their data revealed that OsWRKY13, WRKY42, and
WRKY45-2 interact with each other in a sequential transcriptional regulatory cascade
350
L. S. Rajput et al.