Sodium Distribution in Rough Lemon and Trifoliate Orange Seedlings

Comparative expression of candidate genes involved in sodium transport and compartmentation in citrus

“…A. thaliana plants over-expressing AtHKT1;1 in root stele cells accumulated less salt in the shoot and became more salt tolerant (Møller et al, 2009), while mutants lacking AtHKT1 manifested a consistent increment of Na + in aerial parts with a concomitant reduction in Na + root content (Mäser et al, 2002;Berthomieu et al, 2003). The impaired root-to-shoot Na + translocation in trifoliate orange found in the present study would be in line with previously suggested role of trifoliate orange rootstock in depleting the xylem stream of Na + (Walker, 1986); in fact this rootstock had showed to restrict 22 Na + transport (Elgazzar et al, 1965). Moreover, higher Na + concentrations were found in xylem of Na + -sensitive rough lemon when compared to Rangpur lime plants grown in 50 mM NaCl (Storey, 1995).…”

“…Our results show in fact an increased Cl À root-to-shoot transport rate in trifoliate orange. The increased Cl À sensitivity of trifoliate orange is well documented (Elgazzar et al, 1965;Walker, 1986) and would be responsible for the remarkable reduction in its RGR when compared to Cleopatra mandarin, which is considered the best Cl À excluder genotype among citrus (Cole, 1985;Bañuls and Primo-Millo, 1995;Storey and Walker, 1999;Levy and Syvertsen, 2004). Also lower biomass production has been reported in other Cl-sensitive rootstocks when compared to tolerant ones under saline conditions (Zekri and Parsons, 1992;Lea-Cox and Syvertsen, 1993;Fernández-Ballester et al, 2003;García-Sánchez and Syvertsen, 2006).…”

“…Moreover, citrus rootstocks widely differ in their ability to restrict uptake and/or transport of Cl À and Na + (Grieve and Walker, 1983;Walker, 1986;Bañuls and Primo-Millo, 1995). In this sense, there are indeed rootstocks exhibiting high absorption of Na + and Cl À exclusion, such is the case of Cleopatra mandarin, while others behave the other way around, i.e., Poncirus trifoliata and its hybrids, which accumulate Cl À but are efficient Na + excluders at low salinities (Elgazzar et al, 1965;Walker, 1986;Zekri and Parsons, 1992;Levy and Syvertsen, 2004).…”

Effects of sodium chloride and polyethylene glycol on the water relations, growth, and morphology of citrus rootstock seedlings / by Mongi Zerki.

“…Trifoliate orange appears to be a sodium excluder (Elgazzar et al, 1965; Grieve Walker, 1986) and Citrus macrophylla a boron excluder (Cooper and Peynado, 1959;Embleton et al 1962). This suggests the existence of a blocking mechanism in the transport of these ions (Fernandez et al, 1977).…”

Managing Salinity in Citrus

“…'Rangpur' lime (C. limonia) and 'Cleopatra' mandarin (C. reshnii) appear to be Cl excluders (Cooper, 1961;Cooper and Peynado, 1959;Grieve and Walker, 1983;Hewitt and Furr, 1965;Walker et al, 1983;Wutscher et al, 1973;Zekri and Parsons, 1992). Trifoliate orange (Poncirus trifoliata) and its hybrids appear to be Na excluders (Grieve and Walker, 1983;El Gazzar et al, 1965;Zekri and Parsons, 1992), and C. macrophylla a B excluder (Cooper and Peynado, 1959;Embleton et al, 1962). This suggests the existence of a blocking mechanism in the transport of these ions.…”