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Root vacuolar Na+ sequestration but not exclusion from uptake correlates with barley salt tolerance

Citation

Wu, H and Shabala, L and Zhou, M and Su, N and Wu, Q and Ul-Haq, T and Zhu, J and Mancuso, S and Azzarello, E and Shabala, S, Root vacuolar Na+ sequestration but not exclusion from uptake correlates with barley salt tolerance, The Plant Journal, 100, (1) pp. 55-67. ISSN 0960-7412 (2019) [Refereed Article]


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DOI: doi:10.1111/tpj.14424

Abstract

Soil salinity is a major constraint for the global agricultural production. For many decades, Na+ exclusion from uptake has been the key trait targeted in breeding programs; yet, no major breakthrough in creating salt‐tolerant germplasm was achieved. In this work, we have combined the microelectrode ion flux estimation (MIFE) technique for non‐invasive ion flux measurements with confocal fluorescence dye imaging technique to screen 45 accessions of barley to reveal the relative contribution of Na+ exclusion from the cytosol to the apoplast and its vacuolar sequestration in the root apex, for the overall salinity stress tolerance. We show that Na+/H+ antiporter‐mediated Na+ extrusion from the root plays a minor role in the overall salt tolerance in barley. At the same time, a strong and positive correlation was found between root vacuolar Na+ sequestration ability and the overall salt tolerance. The inability of salt‐sensitive genotypes to sequester Na+ in root vacuoles was in contrast to significantly higher expression levels of both HvNHX1 tonoplast Na+/H+ antiporters and HvVP1 H+‐pumps compared with tolerant genotypes. These data are interpreted as a failure of sensitive varieties to prevent Na+ back‐leak into the cytosol and existence of a futile Na+ cycle at the tonoplast. Taken together, our results demonstrated that root vacuolar Na+ sequestration but not exclusion from uptake played the main role in barley salinity tolerance, and suggested that the focus of the breeding programs should be shifted from targeting genes mediating Na+ exclusion from uptake by roots to more efficient root vacuolar Na+ sequestration.

Item Details

Item Type:Refereed Article
Keywords:barley, salinity, Na+ extrusion, root elongation zone, salinity stress tolerance, tonoplast futile cycle, vacuolar Na+ sequestration
Research Division:Agricultural and Veterinary Sciences
Research Group:Crop and Pasture Production
Research Field:Agro-ecosystem Function and Prediction
Objective Division:Plant Production and Plant Primary Products
Objective Group:Winter Grains and Oilseeds
Objective Field:Barley
UTAS Author:Wu, H (Mr Honghong Wu)
UTAS Author:Shabala, L (Associate Professor Lana Shabala)
UTAS Author:Zhou, M (Professor Meixue Zhou)
UTAS Author:Su, N (Mrs Nana Su)
UTAS Author:Wu, Q (Mr Qi Wu)
UTAS Author:Zhu, J (Miss Juan Zhu)
UTAS Author:Shabala, S (Professor Sergey Shabala)
ID Code:136229
Year Published:2019
Web of Science® Times Cited:4
Deposited By:Zoology
Deposited On:2019-12-09
Last Modified:2020-01-07
Downloads:0

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