fundamental for biotic and abiotic stress adaptation and crop improvement schemes
to raise stress-tolerant plants.
Addition of cis element is supportive for effectual expression of synthetic
promoters to: i) reduce its off-target gene expression, ii) make the synthetic promoter
more functional, iii) improve synthetic promoter strength. EL17—a W-box
cis-acting element (in the promoter of pathogen responding gene ELI17 related to
parsley) and cis-acting element F against fungal infection are important for designing
synthetic promoters to regulate transcription of genes linked with pathogenic
defence mechanisms in plants (Aysha et al. 2018). Shokouhifar et al. (2011) used
F and EL17 in dimers to be placed upstream of the minimal CaMV 35S promoter.
The resulting constructs of synthetic pathogen-inducible promoters in canola (Brassica napus) plants responded significantly to phytohormone treatments and fungal
elicitors. Moradyar et al. (2016) demonstrated that the synthetic pathogen-inducible
promoter SP-DDEE (having parsley D, E17 elements and a minimal promoter)
significantly reduced the development of pathogenic attack by Sclerotinia
sclerotiorum. Pathogen-inducible promoters like WUN-box, MYB, bZIP, ERF,
WRKY and MYC TFs are appropriate candidates in providing defence during the
primary stages of pathogen colonization or subsequent to the invasion of insects.
Cold stress-inducible promoters like rd29A, Arabidopsis COR gene promoters like
cor47, cor6.6, and core 15a are characterized to cut down unfavourable effects
under diverse environmental circumstances. Wsi18 and OsNCED3 genes promoters
have been found to be extremely inducible by ABA, drought, and high salt doses in
transgenic rice (Bang et al. 2013). Hou et al. (2012) demonstrated the activity of
three inducible synthetic promoters—EKCM, EKCRM and ECCRM (linked to the
GUS reporter gene), having multiple cis-acting elements that drive cold and salt
stress-inducible transgene expression with negligible negative impact on transgenic
Arabidopsis (GUS activity under stress was significantly higher in transgenic
plants). Ranjan and Dey (2012) engineered the EFCFS promoter by inserting extra
copies of the stress-inducible ‘AAAG’ cis-motif (Dof-1) to engender hybrid–synthetic promoters—EFCFS-HS-1 containing 10 ‘AAAG’ motif. In the presence of
abiotic stress elicitors, salicylic acid and jasmonic acid, these promoters
demonstrated improved activity compared to conventional constitutive promoters
like EFCFS and the CaMV35S promoters. This study signifies the importance of de
novo hybrid–synthetic promoter in the upcoming engineering of wide range of
agronomically significant plants for sustainable agriculture in marginal soils facing
abiotic and biotic stresses. Lepidopteran insects resistant transgenic tomatoes were
designed from the modified insecticidal cry1Ac gene of Bacillus thuringiensis. Pcec
predicts higher GUS expression in these transgenic plants as the Pcec expression
cassette comprised of the synthetic constitutive promoter Pmec and transcription
activation module for superior GUS expression (Sawant et al. 2001). Widespread
DNA binding sites can be placed in different synthetic promoters for exploiting a
regulated and selective expression pattern, (Petolino and Davies 2013; Aysha et al.
2018). Engineering C3 plants with CAM-related genes can be potent enough to
improve their water use efficiency (WUE) and drought resistance (Borland et al.,
2014; Yang et al., 2015). Relocating CAM carboxylation and decarboxylation genes
458
P. Singla
to raise stress-tolerant plants.
Addition of cis element is supportive for effectual expression of synthetic
promoters to: i) reduce its off-target gene expression, ii) make the synthetic promoter
more functional, iii) improve synthetic promoter strength. EL17—a W-box
cis-acting element (in the promoter of pathogen responding gene ELI17 related to
parsley) and cis-acting element F against fungal infection are important for designing
synthetic promoters to regulate transcription of genes linked with pathogenic
defence mechanisms in plants (Aysha et al. 2018). Shokouhifar et al. (2011) used
F and EL17 in dimers to be placed upstream of the minimal CaMV 35S promoter.
The resulting constructs of synthetic pathogen-inducible promoters in canola (Brassica napus) plants responded significantly to phytohormone treatments and fungal
elicitors. Moradyar et al. (2016) demonstrated that the synthetic pathogen-inducible
promoter SP-DDEE (having parsley D, E17 elements and a minimal promoter)
significantly reduced the development of pathogenic attack by Sclerotinia
sclerotiorum. Pathogen-inducible promoters like WUN-box, MYB, bZIP, ERF,
WRKY and MYC TFs are appropriate candidates in providing defence during the
primary stages of pathogen colonization or subsequent to the invasion of insects.
Cold stress-inducible promoters like rd29A, Arabidopsis COR gene promoters like
cor47, cor6.6, and core 15a are characterized to cut down unfavourable effects
under diverse environmental circumstances. Wsi18 and OsNCED3 genes promoters
have been found to be extremely inducible by ABA, drought, and high salt doses in
transgenic rice (Bang et al. 2013). Hou et al. (2012) demonstrated the activity of
three inducible synthetic promoters—EKCM, EKCRM and ECCRM (linked to the
GUS reporter gene), having multiple cis-acting elements that drive cold and salt
stress-inducible transgene expression with negligible negative impact on transgenic
Arabidopsis (GUS activity under stress was significantly higher in transgenic
plants). Ranjan and Dey (2012) engineered the EFCFS promoter by inserting extra
copies of the stress-inducible ‘AAAG’ cis-motif (Dof-1) to engender hybrid–synthetic promoters—EFCFS-HS-1 containing 10 ‘AAAG’ motif. In the presence of
abiotic stress elicitors, salicylic acid and jasmonic acid, these promoters
demonstrated improved activity compared to conventional constitutive promoters
like EFCFS and the CaMV35S promoters. This study signifies the importance of de
novo hybrid–synthetic promoter in the upcoming engineering of wide range of
agronomically significant plants for sustainable agriculture in marginal soils facing
abiotic and biotic stresses. Lepidopteran insects resistant transgenic tomatoes were
designed from the modified insecticidal cry1Ac gene of Bacillus thuringiensis. Pcec
predicts higher GUS expression in these transgenic plants as the Pcec expression
cassette comprised of the synthetic constitutive promoter Pmec and transcription
activation module for superior GUS expression (Sawant et al. 2001). Widespread
DNA binding sites can be placed in different synthetic promoters for exploiting a
regulated and selective expression pattern, (Petolino and Davies 2013; Aysha et al.
2018). Engineering C3 plants with CAM-related genes can be potent enough to
improve their water use efficiency (WUE) and drought resistance (Borland et al.,
2014; Yang et al., 2015). Relocating CAM carboxylation and decarboxylation genes
458
P. Singla