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Comparing essentiality of SOS1-Mediated Na+ exclusion in salinity tolerance between cultivated and wild Rice species

Citation

Shahzad, B and Shabala, L and Zhou, Meixue and Venkataraman, G and Solis, CA and Page, D and Chen, Zhonghua and Shabala, S, Comparing essentiality of SOS1-Mediated Na+ exclusion in salinity tolerance between cultivated and wild Rice species, International Journal of Molecular Sciences, 23, (17) Article 9900. ISSN 1422-0067 (2022) [Refereed Article]


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2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) license (https:// creativecommons.org/licenses/by/ 4.0/).

DOI: doi:10.3390/ijms23179900

Abstract

Soil salinity is a major constraint that affects plant growth and development. Rice is a staple food for more than half of the human population but is extremely sensitive to salinity. Among the several known mechanisms, the ability of the plant to exclude cytosolic Na+ is strongly correlated with salinity stress tolerance in different plant species. This exclusion is mediated by the plasma membrane (PM) Na+/H+ antiporter encoded by Salt Overly Sensitive (SOS1) gene and driven by a PM H+-ATPase generated proton gradient. However, it is not clear to what extent this mechanism is operational in wild and cultivated rice species, given the unique rice root anatomy and the existence of the bypass flow for Na+. As wild rice species provide a rich source of genetic diversity for possible introgression of abiotic stress tolerance, we investigated physiological and molecular basis of salinity stress tolerance in Oryza species by using two contrasting pairs of cultivated (Oryza sativa) and wild rice species (Oryza alta and Oryza punctata). Accordingly, dose- and age-dependent Na+ and H+ fluxes were measured using a non-invasive ion selective vibrating microelectrode (the MIFE technique) to measure potential activity of SOS1-encoded Na+/H+ antiporter genes. Consistent with GUS staining data reported in the literature, rice accessions had (~4-6-fold) greater net Na+ efflux in the root elongation zone (EZ) compared to the mature root zone (MZ). Pharmacological experiments showed that Na+ efflux in root EZ is suppressed by more than 90% by amiloride, indicating the possible involvement of Na+/H+ exchanger activity in root EZ. Within each group (cultivated vs. wild) the magnitude of amiloride-sensitive Na+ efflux was higher in tolerant genotypes; however, the activity of Na+/H+ exchanger was 2-3-fold higher in the cultivated rice compared with their wild counterparts. Gene expression levels of SOS1, SOS2 and SOS3 were upregulated under 24 h salinity treatment in all the tested genotypes, with the highest level of SOS1 transcript detected in salt-tolerant wild rice genotype O. alta (~5-6-fold increased transcript level) followed by another wild rice, O. punctata. There was no significant difference in SOS1 expression observed for cultivated rice (IR1-tolerant and IR29-sensitive) under both 0 and 24 h salinity exposure. Our findings suggest that salt-tolerant cultivated rice relies on the cytosolic Na+ exclusion mechanism to deal with salt stress to a greater extent than wild rice, but its operation seems to be regulated at a post-translational rather than transcriptional level.

Item Details

Item Type:Refereed Article
Keywords:wild rice salinity tolerance
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Crop and pasture production
Research Field:Agrochemicals and biocides (incl. application)
Objective Division:Plant Production and Plant Primary Products
Objective Group:Grains and seeds
Objective Field:Wheat
UTAS Author:Shahzad, B (Mr Babar Shahzad)
UTAS Author:Shabala, L (Associate Professor Lana Shabala)
UTAS Author:Zhou, Meixue (Professor Meixue Zhou)
UTAS Author:Solis, CA (Ms Celymar Solis)
UTAS Author:Page, D (Mr David Page)
UTAS Author:Chen, Zhonghua (Mr Zhonghua Chen)
UTAS Author:Shabala, S (Professor Sergey Shabala)
ID Code:154329
Year Published:2022
Web of Science® Times Cited:1
Deposited By:TIA - Research Institute
Deposited On:2022-11-23
Last Modified:2022-12-19
Downloads:0

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