Expression of SOD and APX genes positively regulates secondary cell wall biosynthesis and promotes plant growth and yield in Arabidopsis under salt stress

Abstract

Abiotic stresses cause accumulation of reactive oxygen species (ROS), such as hydrogen peroxide (H2O2) in plants. Sophisticated mechanisms are required to maintain optimum level of H2O2 that acts as signalling molecule regulating adaptive response to salt stress. CuZn-superoxide dismutase (CuZn-SOD) and ascorbate peroxidase (APX) constitute first line of defence against oxidative stress. In the present study, PaSOD and RaAPX genes from Potentilla atrosanguinea and Rheum australe, respectively were overexpressed individually as well as in combination in Arabidopsis thaliana. Interestingly, PaSOD and dual transgenic lines exhibit enhanced lignin deposition in their vascular bundles with altered S:G ratio under salt stress. RNA-seq analysis revealed that expression of PaSOD gene in single and dual transgenics positively regulates expression of lignin biosynthesis genes and transcription factors (NACs, MYBs, C3Hs and WRKY), leading to enhanced and ectopic deposition of lignin in vascular tissues with larger xylem fibres and alters S:G ratio, as well. In addition, transgenic plants exhibit growth promotion, higher biomass production and increased yield under salt stress as compared to wild type plants. Our results suggest that in dual transgenics, ROS generated during salt stress gets converted into H2O2 by SOD and its optimum level was maintained by APX. This basal level of H2O2 acts as messenger for transcriptional activation of lignin biosynthesis in vascular tissue, which provides mechanical strength to plants. These findings reveal an important role of PaSOD and RaAPX in enhancing salt tolerance of transgenic Arabidopsis via increased accumulation of compatible solutes and by regulating lignin biosynthesis.

Soil Amendment with Raw Garlic Stalk: A Novel Strategy to Stimulate Growth and the Antioxidative Defense System in Monocropped Eggplant in the North of China

“…The triggering of physiological metabolism and enhanced defense enzymes in eggplant upon treatment with RGS also indicates a priming phenomenon for yield production, as previously shown in cabbages [55]. Moreover, overproduction of SOD has been reported as a plant growth promoter under salt stress conditions [56]. These reports are strongly coherent with our present study.…”

BpNAC012 Positively Regulates Abiotic Stress Responses and Secondary Wall Biosynthesis

“…Several studies have shown that lignin accumulation and high levels of lignin biosynthetic gene expression are important for abiotic stress tolerance (Hu et al, 2009;Shafi et al, 2015;Srivastava et al, 2015). In this study, heavier deposition of lignin was observed specifically in the secondary xylem and phloem fibers of BpNAC012-OE transgenic plants under salt and osmotic stress conditions, which was consistent with the results that BpNAC012 highly induced the expression of lignin biosynthetic genes in response to abiotic stress treatments.…”

Histone acetyltransferase GCN5 contributes to cell wall integrity and salt stress tolerance by altering the expression of cellulose synthesis genes

“…The number of lignified cells in vascular bundles was distinctly greater in plants under salt stress, with maximum expansion of the lignified area found in the root vasculature (S anchez-Aguayo et al, 2004). The expression levels of several key genes involved in the lignin biosynthesis pathway were altered upon salt treatment (Shafi et al, 2015). The increased expression of these proteins might help reduce the bypass water flow that allows Na + ions to enter roots via an apoplastic pathway.…”