Physiological and molecular analyses of seedlings of two Tunisian durum wheat (Triticum turgidum L. subsp. Durum [Desf.]) varieties showing contrasting tolerance to salt stress

Abstract

Salinity is one of the severest environmental stresses affecting plant productivity. In many plant species, salt sensitivity is associated with the accumulation of sodium (Na ? ) in photosynthetic tissues. Here, we provide the physiological and molecular analyses of seedlings of two Tunisian durum wheat genotypes (Triticum turgidum L. subsp. Durum [Desf.]), Mahmoudi (salt sensitive) and Om Rabia3 (salt tolerant). Na ? and K ? contents in leaf sheath from Om Rabia3 were significantly higher than those of Mahmoudi. However, the net uptake of Na ? from the soil occurred at similar rates in both varieties, suggesting that Om Rabia3 has much stronger ability to limit Na ? flux from roots to leaf blades. This mechanism could be explained by a capacity of Om Rabia3 to retain higher Na ? concentration in leaf sheath and unload less Na ? from the xylem to the upper shoots. When treated with 100 mM NaCl leaf sheaths of Om Rabia3 developed lower water potentials and a higher relative water contents than those of Mahmoudi. These features may arise from enhanced osmotic adjustment in Om Rabia3. Measurements of stomatal conductance, free proline and chlorophyll content also indicate that Om Rabia3 is better adapted to tolerate high salt than Mahmoudi. A correlation was obtained between the expression pattern of TaSOS1 (a plasma membrane Na ? /H ? antiporter) in the roots and sheaths of both wheat varieties and the Na ? fluxes from roots to leaves. TaSOS1 transcript accumulated in Mahmoudi than in Om Rabia3, suggesting repression of TaSOS1 in the tolerant variety that reduces loading of Na ? to the upper shoots. These results help to design new genetic screens for salt tolerance in wheat.

Influence of Seaweed Saps on Germination, Growth and Yield of Hybrid Maize under Cauvery Command of Karnataka, India

“…This might be due to inhibition of germination by the high salts concentration of seaweed saps. Salt stress induced inhibition of seed germination, seedling growth and metabolic processes were reported in maize (Azevedo et al, 2004) and wheat (Brini et al, 2009), which corroborated the results of the present study. These results are in agreement with the findings of Gaurav Kumar and Dinabandhu Sahoo (2011).…”

Investigation of the salt tolerance of new Polish bread and durum wheat cultivars

“…Rawat et al (2011) observed a decrease in the germination rate of T. aestivum caryopses in soil with a salt concentration of 0-60 mM, while Hu et al (2012) noted this effect at FW fresh weight, DW dry weight, RWC relative water content 0-200 mM of NaCl. Brini et al (2009) found a significant decrease of caryopses germination of durum wheat under 200 mM of NaCl treatment. It is very interesting that germination ability in salt solutions is negatively correlated with seedling growth.…”

“…In some regions of the world, low annual precipitation necessitates irrigation of crop plants with water which sometimes could not be completely desalted. However, in most cases soil salinity is an effect of salt accumulation over long cultivation periods and deforestation (Brini et al 2009). In Poland, located in Central Europe, the progressive reduction of the groundwater level and more frequent periods of drought cause 30 % losses of grain yield, which results in the need for plant watering (Schar et al 2004;Martyniak et al 2007;Walter et al 2011).…”

Comparison of an antioxidant system in tolerant and susceptible wheat seedlings in response to salt stress

“…In a previous work, the physiological analysis of the two Tunisian durum wheat genotypes showed differential tolerance to salinity (Brini et al, 2009). However, data concerning the effects of salinity on ROS production and antioxidant defense system in these two durum wheat cultivars are still lacking.…”

“…durum), Mahmoudi (salt sensitive) and Om Rabia3 (salt tolerant) were sterilized and then germinated on Petri dishes as described by Brini et al (2009). Three-day-old seedlings were transferred to containers with modified half-strength Hoagland's solution (Epstein, 1972).…”