28 research outputs found
Compatible solute accumulation and stress-mitigating effects in barley genotypes contrasting in their salt tolerance
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 HO (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
(A) The effects of 80 mM NaCl application on membrane potential in the mature zone of 6-d-old Baart 46 seedlings
(B) Steady-state membrane depolarization 60 min after salt application measured in all four cultivars. Mean ±SE (=6).<p><b>Copyright information:</b></p><p>Taken from "A root's ability to retain K correlates with salt tolerance in wheat"</p><p></p><p>Journal of Experimental Botany 2008;59(10):2697-2706.</p><p>Published online 20 May 2008</p><p>PMCID:PMC2486465.</p><p></p
Correlation between net mean K efflux measured from 6-d-old wheat seedlings and final plant yield at harvest (A) and the magnitude of membrane depolarization 60 min after 80 mM NaCl application (B)
Each point represents a different cultivar.<p><b>Copyright information:</b></p><p>Taken from "A root's ability to retain K correlates with salt tolerance in wheat"</p><p></p><p>Journal of Experimental Botany 2008;59(10):2697-2706.</p><p>Published online 20 May 2008</p><p>PMCID:PMC2486465.</p><p></p
Nax loci affect SOS1-like Na/H exchanger expression and activity in wheat
Salinity stress tolerance in durum wheat is strongly associated with a plant’s ability to control Na delivery to the shoot. Two loci, termed Nax1 and Nax2, were recently identified as being critical for this process and the sodium transporters HKT1;4 and HKT1;5 were identified as the respective candidate genes. These transporters retrieve Na from the xylem, thus limiting the rates of Na transport from the root to the shoot. In this work, we show that the Nax loci also affect activity and expression levels of the SOS1-like Na/H exchanger in both root cortical and stelar tissues. Net Na efflux measured in isolated steles from salt-treated plants, using the non-invasive ion flux measuring MIFE technique, decreased in the sequence: Tamaroi (parental line)>Nax1=Nax2>Nax1:Nax2 lines. This efflux was sensitive to amiloride (a known inhibitor of the Na/H exchanger) and was mirrored by net H flux changes. TdSOS1 relative transcript levels were 6–10-fold lower in Nax lines compared with Tamaroi. Thus, it appears that Nax loci confer two highly complementary mechanisms, both of which contribute towards reducing the xylem Na content. One enhances the retrieval of Na back into the root stele via HKT1;4 or HKT1;5, whilst the other reduces the rate of Na loading into the xylem via SOS1. It is suggested that such duality plays an important adaptive role with greater versatility for responding to a changing environment and controlling Na delivery to the shoot
Eight-week-old wheat cultivars used in this study after 6 weeks of salt treatment
The growth of salt-treated plants (shown on the left hand side of each picture) is severely restricted compared with control plants (shown on the right).<p><b>Copyright information:</b></p><p>Taken from "A root's ability to retain K correlates with salt tolerance in wheat"</p><p></p><p>Journal of Experimental Botany 2008;59(10):2697-2706.</p><p>Published online 20 May 2008</p><p>PMCID:PMC2486465.</p><p></p
(A) Net K and H flux kinetics measured in 6-d-old seedlings of Baart 46 cultivar following 80 mM NaCl treatment
Fluxes were measured in the mature zone, about 10 mm from the root tip. Means ±SE (=6). (B) Mean net K flux from each of the four cultivars over the first 60 min after NaCl application (80 mM). Means ±SE (=6). (C) Peak H efflux values measured 2 min after NaCl stress onset in four wheat cultivars. Means ±SE (=6). In all MIFE measurements, the sign convention is efflux negative.<p><b>Copyright information:</b></p><p>Taken from "A root's ability to retain K correlates with salt tolerance in wheat"</p><p></p><p>Journal of Experimental Botany 2008;59(10):2697-2706.</p><p>Published online 20 May 2008</p><p>PMCID:PMC2486465.</p><p></p