title: 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.
authors.affiliation: Division of Biotechnology, CSIR-Institute of Himalayan Bioresource Technology, Palampur, 176061, HP, India.
authors.forename: Amrina
authors.initials: A
authors.lastname: Shafi
authors.forename: Rohit
authors.initials: R
authors.lastname: Chauhan
authors.forename: Tejpal
authors.initials: T
authors.lastname: Gill
authors.forename: Mohit K
authors.initials: MK
authors.lastname: Swarnkar
authors.forename: Yelam
authors.initials: Y
authors.lastname: Sreenivasulu
authors.forename: Sanjay
authors.initials: S
authors.lastname: Kumar
authors.forename: Neeraj
authors.initials: N
authors.lastname: Kumar
authors.forename: Ravi
authors.initials: R
authors.lastname: Shankar
authors.forename: Paramvir Singh
authors.initials: PS
authors.lastname: Ahuja
authors.forename: Anil Kumar
authors.initials: AK
authors.lastname: Singh
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D060387:Ascorbate Peroxidases / Q000235:genetics* / Q000378:metabolism; D053898:Biosynthetic Pathways; D002473:Cell Wall / Q000378:metabolism; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008031:Lignin / Q000378:metabolism; D018384:Oxidative Stress; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018547:Plant Stems / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified; D031987:Potentilla / Q000201:enzymology* / Q000235:genetics; D012250:Rheum / Q000201:enzymology* / Q000235:genetics; D015398:Signal Transduction; D012965:Sodium Chloride / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000235:genetics* / Q000378:metabolism; D059467:Transcriptome; D019076:Transgenes
chemical_list: D000975:Antioxidants; D010940:Plant Proteins; D012965:Sodium Chloride; D008031:Lignin; D006861:Hydrogen Peroxide; D060387:Ascorbate Peroxidases; D013482:Superoxide Dismutase