In Vitro Expression of Sodium Chloride Tolerance of Some Solanum Species

Abstract

Fifteen Solanum species (13 wild potato forms and two
cultivars,Dèsiree and Hansa), representing different degrees of sodium
chloride (NaCl) tolerance, were chosen to study the in vitro expression of
NaCl. Two-node explants from in vitro propagated (on a medium of
Murashige and Skoog (MS) –salts) plantlets were placed in honey jars
containing 50 ml MS supplemented with 0.1mg/l indole acetic acid
(IAA), 0.2 mg/l benzylaminopurine (BAP) and either one of four NaCl
concentrations (0,40,80 and 120 mM/l). They were placed in a culture
room at a temperature of 20°C-23°C, 4000 lux light intensity and 16 hours
light period, and arranged in a complete randomized design with four
replicates. The results showed that shoot growth in all species was
inhibited by increasing NaCl concentration. Analysis of explant shoots
and roots showed that Na+ and Cl - concentrations increased with
increasing NaCl concentration, whereas those of K+ and Ca2+ decreased.
There was a tendency of lower Na+ and Cl - concentrations in the shoots
and higher concentrations in the roots of the NaCl tolerant compared to
sensitive species. K+ concentrations in the shoots and Ca2+ concentrations
in the roots were higher in NaCl tolerant species than in sensitive ones.
Na+ and Cl - concentrations in the shoots and explant main stem length
were negatively correlated (r=- 0.91 for both). The correlation coefficients
between the main stem length and K+ concentration in shoots and
Ca2+ concentrations in the roots were positive and highly significant
(r= 0.74 and r = 0.90, respectively). However, Na+ and Cl - concentrations
in the root were not correlated with shoot length. Shoot length could be a
good trait for a quick screening of potato genotypes for NaCl tolerance