Expression of SOD and APX genes positively regulates secondary cell wall biosynthesis and promotes plant growth and yield in Arabidopsis under salt stress
- 1.9k Downloads
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.
KeywordsAscorbate peroxidase Arabidopsis thaliana CuZn-superoxide dismutase Hydrogen peroxide signalling Lignification RNA-seq Secondary cell wall biosynthesis
This work was supported by Grants from the Council of Scientific and Industrial Research (CSIR), New Delhi, India under CSIR Network Projects: SIMPLE (BSC0109) and PlaGen (BSC0107) and Indo-German Science and Technology Centre (IGSTC), India. A.S. and T.G. acknowledge fellowships awarded by the CSIR, India. Mr. Sanjoy Chanda is acknowledged for technical help in confocal microscopy. We thank Dr. Ivelin Pantchev, Associate Professor, Sofia University, Sofia, Bulgaria for critically reading the manuscript. This paper represents CSIR-IHBT communication number 3567.
- Barrs HD, Weatherley PE (1962) A re-examination of the relative turgidity technique for estimating water deficits in leaves. Aust J Biol Sci 15:413–428Google Scholar
- Desikan R, Clarke A, Hancock JT, Neill SJ (1999) H2O2 activates a MAP kinase-like enzyme in Arabidopsis thaliana suspension cultures. J Exp Bot 50:1863–1866Google Scholar
- Gill T, Kumar S, Ahuja PS, Sreenivasulu Y (2010a) Over-expression of Potentilla superoxide dismutase improves salt stress tolerance during germination and growth in Arabidopsis thaliana. J Plant Genet Transgenics 1:1–10Google Scholar
- Jbir N, Chaïbi W, Ammar S, Jemmali A, Ayadi A (2001) Root growth and lignification of two wheat species differing in their sensitivity to NaCl, in response to salt stress. Compt Rendus Acad Sci III Sci Vie 324:863–868Google Scholar
- Kumar S, Sahoo R, Ahuja PS (2002) Isozyme of autoclavable superoxide dismutase (SOD), a process for the identification and extraction of the SOD in cosmetic, food and pharmaceutical compositions. US Patent No. 6,485950 B1Google Scholar
- Nakano Y, Asada K (1981) Hydrogen peroxide is scavenged by ascorbate-specific peroxidase in spinach chloroplasts. Plant Cell Physiol 22:867–880Google Scholar
- Ruth GA, Neval E, Lenwood SH (2002) Role of superoxide dismutases (SODs) in controlling oxidative stress in plants. J Exp Bot 372:1331–1341Google Scholar
- Sambrook J, Russel DW (2001) Molecular cloning: a laboratory manual, 3rd edn. Cold Spring Harbor laboratory Press, New YorkGoogle Scholar
- Tang L, Kwon SY, Kim SY, Kim JS, Choi JS, Kwang YC, Sung CK, Kwak SS, Lee HS (2006) Enhanced tolerance of transgenic potato plants expressing both superoxide dismutase and ascorbate peroxidase in chloroplasts against oxidative stress and high temperature. Plant Cell Rep 25:1380–1386CrossRefPubMedGoogle Scholar