title: Compatible solute accumulation and stress-mitigating effects in barley genotypes contrasting in their salt tolerance.
abstract: The accumulation of compatible solutes is often regarded as a basic strategy for the protection and survival of plants under abiotic stress conditions, including both salinity and oxidative stress. In this work, a possible causal link between the ability of contrasting barley genotypes to accumulate/synthesize compatible solutes and their salinity stress tolerance was investigated. The impact of H(2)O(2) (one of the components of salt stress) on K(+) flux (a measure of stress 'severity') and the mitigating effects of glycine betaine and proline on NaCl-induced K(+) efflux were found to be significantly higher in salt-sensitive barley genotypes. At the same time, a 2-fold higher accumulation of leaf and root proline and leaf glycine betaine was found in salt-sensitive cultivars. The total amino acid content was also less affected by salinity in salt-tolerant cultivars. In these, potassium was found to be the main contributor to cytoplasmic osmolality, while in salt-sensitive genotypes, glycine betaine and proline contributed substantially to cell osmolality, compensating for reduced cytosolic K(+). Significant negative correlations (r= -0.89 and -0.94) were observed between Na(+)-induced K(+) efflux (an indicator of salt tolerance) and leaf glycine betaine and proline. These results indicate that hyperaccumulation of known major compatible solutes in barley does not appear to play a major role in salt-tolerance, but rather, may be a symptom of salt-susceptibility.
authors.affiliation: School of Agricultural Science, Private Bag 54, University of Tasmania, Hobart, TAS 7001, Australia.
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Chen
authors.forename: Tracey A
authors.initials: TA
authors.lastname: Cuin
authors.forename: Meixue
authors.initials: M
authors.lastname: Zhou
authors.forename: Amanda
authors.initials: A
authors.lastname: Twomey
authors.forename: Bodapati P
authors.initials: BP
authors.lastname: Naidu
authors.forename: Sergey
authors.initials: S
authors.lastname: Shabala
mesh_terms: D000222:Adaptation, Physiological; D001622:Betaine / Q000378:metabolism*; D005838:Genotype; D001467:Hordeum / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D011392:Proline / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology*; D013402:Sugar Alcohols / Q000378:metabolism*
chemical_list: D017382:Reactive Oxygen Species; D013402:Sugar Alcohols; D001622:Betaine; D012965:Sodium Chloride; D011392:Proline; D011188:Potassium