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.

Some rootstocks improve pepper tolerance to mild salinity through ionic regulation

“…In contrast at T2, strong proline synthesis took place in the ungrafted and A/5 plants when compared 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 caused by salt stress [1,29], which has been observed in different grafted plants like tomato [49], cucumber [29] or tobacco [50]. Conversely, the concomitant increase in proline with a prolonged exposure time in the ungrafted and A/5 plants was consistent with the higher leaf proline concentrations in salt-sensitive genotypes reported for other species such as wheat [51], barley [52], Centaurea ragusina [45] or rice [53]. This indicates that significant proline accumulation generally occurs only beyond the salt stress threshold [54].…”

Effect of Salt Stress on Na Accumulation, Antioxidant Enzyme Activities and Activity of Cell Wall Peroxidase of Huckleberry (Solanum scabrum) and Eggplant (Solanum melongena)

“…Oxidative stress has also been shown to induce K + efflux from roots under salinity stress , a phenomenon that is thought to negatively affect growth (Shabala et al, 2005;Chen et al, 2007). In the present study, K + decreased in leaf and root of both plants, but the decrease was more marked in eggplant than in huckleberry, especially in the root (Table 2), where there was a corresponding elevated Na + /K + ratio (Fig.…”

TaCHP: A Wheat Zinc Finger Protein Gene Down-Regulated by Abscisic Acid and Salinity Stress Plays a Positive Role in Stress Tolerance

“…These events are typically accompanied by the accumulation of reactive oxygen species (ROS), which interact with a variety of molecules to cause irreversible cell damage, necrosis, and death (Girotti, 2001). Salinity-sensitive barley (Hordeum vulgare) cultivars appear to be particularly susceptible to ROS-induced damage (Chen et al, 2007), and the ability to neutralize ROS has therefore been proposed as an important component of stress tolerance (Xue et al, 2009). It was reported that higher POD activity can alleviate more rapid and severe ROS changes (Laloi et al, 2004).…”