Ectopic expression of SOD and APX genes in Arabidopsis alters metabolic pools and genes related to secondary cell wall cellulose biosynthesis and improve salt tolerance
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Hydrogen peroxide (H2O2) is known to accumulate in plants during abiotic stress conditions and also acts as a signalling molecule. In this study, Arabidopsis thaliana transgenics overexpressing cytosolic CuZn-superoxide dismutase (PaSOD) from poly-extremophile high-altitude Himalayan plant Potentilla atrosanguinea, cytosolic ascorbate peroxidase (RaAPX) from Rheum australe and dual transgenics overexpressing both the genes were developed and analyzed under salt stress. In comparison to wild-type (WT) or single transgenics, the performance of dual transgenics under salt stress was better with higher biomass accumulation and cellulose content. We identified genes involved in cell wall biosynthesis, including nine cellulose synthases (CesA), seven cellulose synthase-like proteins together with other wall-related genes. RNA-seq analysis and qPCR revealed differential regulation of genes (CesA 4, 7 and 8) and transcription factors (MYB46 and 83) involved in secondary cell wall cellulose biosynthesis, amongst which most of the cellulose biosynthesis gene showed upregulation in single (PaSOD line) and dual transgenics at 100 mM salt stress. A positive correlation between cellulose content and H2O2 accumulation was observed in these transgenic lines. Further, cellulose content was 1.6–2 folds significantly higher in PaSOD and dual transgenic lines, 1.4 fold higher in RaAPX lines as compared to WT plants under stress conditions. Additionally, transgenics overexpressing PaSOD and RaAPX also displayed higher amounts of phenolics as compared to WT. The novelty of present study is that H2O2 apart from its role in signalling, it also provides mechanical strength to plants and aid in plant biomass production during salt stress by transcriptional activation of cellulose biosynthesis pathway. This modulation of the cellulose biosynthetic machinery in plants has the potential to provide insight into plant growth, morphogenesis and to create plants with enhanced cellulose content for biofuel use.
KeywordAPX CuZn-SOD Cell wall biosynthesis Flavonoids H2O2 signalling Salinity
This research was supported by grants from the Council of Scientific and Industrial Research (CSIR), New Delhi, India under CSIR Network Projects BSC107 and BSC109.
AKS, AS and PSA conceived and designed the experiments. AS and TG performed the experiments. PSA, YS, SK and AKS analyzed the data. IZ did statistical analysis. AS and AKS wrote the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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