Abstract
WRKY proteins are superfamily of transcription factors, which are up or down-regulated in response to biotic and abiotic stress though limited study has conducted on transcriptional repression of tomato WRKY genes to salt stress. Thus, this study was conducted on three transgenic tomato ( Solanum lycopersicum L. cv. Moneymaker) T1 generation plants carrying RNAi constructs for WRKY5, WRKY12, and WRKY13 to identify WRKYs that can act as negative regulators and uncover associated gene expression. In vitro propagated transgenic and wild type (MM) seedlings were transferred to pots under greenhouse. The plants were watered with standard solution supplemented with 0 or 100 mM NaCl for 4 weeks and evaluated for their responses. The result showed WRKY12 and WRKY13_RNAi lines performed better under salt stress with successful silencing which suggest the two WRKY transcription factors act as negative regulators. SOS1 is up regulated in WRKY13_RNAi, which may lead to low Na + accumulation and contribute to salt tolerance. Expression of APX is up regulated in WRKY12 and WRKY13_RNAi, which may contribute to salt tolerance mechanism of the two genotypes. Microarray analysis of abiotic stress related genes might give clear indication for the regulatory role of WRKY12 and WRKY13 in abiotic stress tolerance. Keywords ׃ Solanum lycopersicum . Salt Stress. WRKY _ RNAi. Negative Regulator DOI: 10.7176/JBAH/10-17-03 Publication date: September 30 th 2020
Highlights
Transcription factors are proteins which have substantial role in regulating stress-inducible gene expression enabling plants to adapt biotic and abiotic stresses (Besseau et al, 2012; Chen et al, 2012; Gao et al, 2007; Singh et al, 2002)
Though variation was found among different WRKY transgenes, the results here showed that the shoot length and biomass production were drastically reduced under salt stress compared to control
The necrotic and yellowish leaf phenotype of WRKY5-3-RNA interference (RNAi) might be related to program cell death induced by higher expression of metacaspase -1 (MCA1) and/or reactive oxygen species (ROS) production as signaling molecule. This preliminary result shows that WRKY12 and WRKY13-RNAi lines performed better under salt stress with successful silencing which suggest that the two WRKY TFs act as negative regulators in salt stress tolerance in tomato
Summary
Transcription factors are proteins which have substantial role in regulating stress-inducible gene expression enabling plants to adapt biotic and abiotic stresses (Besseau et al, 2012; Chen et al, 2012; Gao et al, 2007; Singh et al, 2002). WRKY proteins are a superfamily of transcription factors containing one or two highly conserved WRKY domains, 60 amino acid region comprising conserved WRKYGQK sequences at N-terminal together with zinc-finger-like motif at its C-terminal (Eulgem et al, 2000). They are known to be involved in regulating diverse functional processes such as growth, development, hormone-mediated pathways, biotic and abiotic stresses (Ramamoorthy et al, 2008). Studies indicated that there are 74 members of WRKY genes in Arabidopsis (Arabidopsis thaliana), 64 in soybean (Glycine max), 81 in tomato, 102 and 98 in indica and japonica rice, respectively (Huang et al, 2012; Ross et al, 2007; Ülker and Somssich, 2004; Zhou et al, 2008)
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