%A Wu,Honghong
%A Shabala,Lana
%A Liu,Xiaohui
%A Azzarello,Elisa
%A Zhou,Meixue
%A Pandolfi,Camilla
%A Chen,Zhong-Hua
%A Bose,Jayakumar
%A Mancuso,Stefano
%A Shabala,Sergey
%D 2015
%J Frontiers in Plant Science
%C
%F
%G English
%K bread wheat,cytosolic Na+,Na+ distribution,root zones,salinity stress tolerance,vacuolar Na+ sequestration
%Q
%R 10.3389/fpls.2015.00071
%W
%L
%M
%P
%7
%8 2015-February-20
%9 Original Research
%+ Prof Sergey Shabala,Faculty of Science, Engineering and Technology, School of Land and Food, University of Tasmania,Hobart, TAS, Australia,Sergey.Shabala@utas.edu.au
%#
%! Vacuolar Na+ sequestration in wheat
%*
%<
%T Linking salinity stress tolerance with tissue-specific Na+ sequestration in wheat roots
%U https://www.frontiersin.org/articles/10.3389/fpls.2015.00071
%V 6
%0 JOURNAL ARTICLE
%@ 1664-462X
%X Salinity stress tolerance is a physiologically complex trait that is conferred by the large array of interacting mechanisms. Among these, vacuolar Na+ sequestration has always been considered as one of the key components differentiating between sensitive and tolerant species and genotypes. However, vacuolar Na+ sequestration has been rarely considered in the context of the tissue-specific expression and regulation of appropriate transporters contributing to Na+ removal from the cytosol. In this work, six bread wheat varieties contrasting in their salinity tolerance (three tolerant and three sensitive) were used to understand the essentiality of vacuolar Na+ sequestration between functionally different root tissues, and link it with the overall salinity stress tolerance in this species. Roots of 4-day old wheat seedlings were treated with 100 mM NaCl for 3 days, and then Na+ distribution between cytosol and vacuole was quantified by CoroNa Green fluorescent dye imaging. Our major observations were as follows: (1) salinity stress tolerance correlated positively with vacuolar Na+ sequestration ability in the mature root zone but not in the root apex; (2) contrary to expectations, cytosolic Na+ levels in root meristem were significantly higher in salt tolerant than sensitive group, while vacuolar Na+ levels showed an opposite trend. These results are interpreted as meristem cells playing a role of the “salt sensor;” (3) no significant difference in the vacuolar Na+ sequestration ability was found between sensitive and tolerant groups in either transition or elongation zones; (4) the overall Na+ accumulation was highest in the elongation zone, suggesting its role in osmotic adjustment and turgor maintenance required to drive root expansion growth. Overall, the reported results suggest high tissue-specificity of Na+ uptake, signaling, and sequestration in wheat roots. The implications of these findings for plant breeding for salinity stress tolerance are discussed.