Evaluating contribution of ionic, osmotic and oxidative stress components towards salinity tolerance in barley.
BACKGROUND
Salinity tolerance is a physiologically multi-faceted trait attributed to multiple mechanisms. Three barley (Hordeum vulgare) varieties contrasting in their salinity tolerance were used to assess the relative contribution of ionic, osmotic and oxidative stress components towards overall salinity stress tolerance in this species, both at the whole-plant and cellular levels. In addition, transcriptional changes in the gene expression profile were studied for key genes mediating plant ionic and oxidative homeostasis (NHX; RBOH; SOD; AHA and GORK), to compare a contribution of transcriptional and post-translational factors towards the specific components of salinity tolerance.


RESULTS
Our major findings are two-fold. First, plant tissue tolerance was a dominating component that has determined the overall plant responses to salinity, with root K(+) retention ability and reduced sensitivity to stress-induced hydroxyl radical production being the main contributing tolerance mechanisms. Second, it was not possible to infer which cultivars were salinity tolerant based solely on expression profiling of candidate genes at one specific time point. For the genes studied and the time point selected that transcriptional changes in the expression of these specific genes had a small role for barley's adaptive responses to salinity.


CONCLUSIONS
For better tissue tolerance, sodium sequestration, K(+) retention and resistance to oxidative stress all appeared to be crucial. Because these traits are highly interrelated, it is suggested that a major progress in crop breeding for salinity tolerance can be achieved only if these complementary traits are targeted at the same time. This study also highlights the essentiality of post translational modifications in plant adaptive responses to salinity.
Getnet Dino
GD
Adem
Stuart J
SJ
Roy
Meixue
M
Zhou
John P
JP
Bowman
School of Land and Food, University of Tasmania, Private Bag 54, Hobart Tas 7001, Australia. Sergey.Shabala@utas.edu.au.
Sergey
S
Shabala
D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D001467:Hordeum / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D017665:Hydroxyl Radical / Q000378:metabolism; D007477:Ions; D007700:Kinetics; D009995:Osmosis / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D011522:Protons; D055049:Salt Tolerance / Q000187:drug effects / Q000235:genetics; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects
D007477:Ions; D010940:Plant Proteins; D011522:Protons; D017665:Hydroxyl Radical; D012965:Sodium Chloride; D012964:Sodium; D011188:Potassium