Contribution of inorganic cations and organic compounds to osmotic adjustment in root cultures of two Centaurium species differing in tolerance to salt stress

Abstract

The effect of reduced availability of sugars on growth and essential metabolic processes in roots, resulting from decreased photosynthesis under salinity, was excluded by establishing a non-photosynthetic model-system in this study: root cultures of Centaurium maritimum (L.) Fritch and Centaurium spicatum (L.) Fritch. The contribution of inorganic cations and organic compounds (e.g. carbohydrates and amino acids) to the osmotic adjustment (OA) in roots during short-term exposure to various salt concentrations (0, 50, 100 or 200 mM NaCl) was emphasized. Observed morphological and histological changes in roots were species specific, and were dependent on salinity level. Although C. spicatum appears to be more tolerant to salt stress, both species employed similar strategies in response to elevated salinity to different extents, and displayed effective OA mechanisms. Under low and moderate salinity, inorganic cations were the major contributors to OA in roots of both species, followed by soluble sugars, while the relative contribution of proline (Pro) and free amino acids was insignificant. Osmotic adjustment under severe stress appears to be mediated by increased accumulation of organic compounds. The analysis of the intraspecies variability in salt response of C. spicatum and C. maritimum roots enabled the identification of some organic compounds which could be used as potential biochemical markers in screening for salt tolerance, including Pro in C. spicatum, and trehalose and polyols in C. maritimum.

Osmotic Adjustment in Roots and Leaves of two Cotton Cultivars with Different Tolerance to Soil Salinity

“…The patterns we observed in K + concentrations are consistent with the results of Zhong and Lauchli [30] who found that 150 mol m-3 NaCl greatly reduced the deposition rates of K + in cotton roots. Alternatively, the salt-induced decrease in leaf and root K + concentrations may be attributed to K + competition with Na + on the root plasma membrane, as suggested by Aslam et al [31]. If true, then the salt-tolerant cotton cultivar in this study may possess a K/Na discrimination mechanism similar to what has been reported for wheat (Gorham, 1994).…”

Silicon improves salt tolerance by increasing root water uptake in Cucumis sativus L.

“…Therefore, the role of osmotic driving force in silicon-mediated enhancement of water uptake under stress conditions is genotype dependent and may also be related to stress types. The decrease of root xylem osmotic potential, i.e., osmotic adjustment, results from the accumulation of compatible organic solutes (Parida and Das 2005;Ming et al 2012;Mišić et al 2012). Soluble sugar is one of the most important compatible organic solutes in the osmotic adjustment (Zhu and Gong 2014).…”

Halophytic herbs of the Mediterranean basin: An alternative approach to health

“…Botanical aspects Sea centaury (Centaurium maritimum (L.) Fritsch) and common centaury (C. erythrea Rafn) are widely distributed in the Mediterranean region, while they can also be found in saline soils (Mišić et al, 2009;Šiler et al, 2014). According to Mišić et al (2012) C. maritimum responds to salinity and water deficit through osmoregulatory mechanisms by synthesizing trehalose and polyols which are the main components of plant defense against salt stress.…”