Abstract

In this work, the effect of different concentrations of NaCl on calli induced from two sugarcane cultivars NCo310 and CP59-73 was studied. Growth and ion concentrations (Na⁺, Cl^-, K⁺ and Ca²⁺) of calli were determined after 1, 2 and 3 months of stress with the objective to understand the cellular mechanisms operating in salt stress tolerance and to determine the implication of inorganic fraction in salt tolerance in sugarcane cultivars. A negative effect of the NaCl concentration and the duration of stress exposure on the callus rate growth was observed in both cultivars and with more extent in CP59-73 cv. Results showed an increase in Na⁺ and Cl^– and a decrease in K⁺ and Ca²⁺ concentrations after 1, 2 and 3 months of salt stress exposure. It also showed that resistant cv. NCo310 stressed calli accumulated less Na⁺ and retained more K⁺ and Ca²⁺ than CP59-73 calli. Cl^- appeared to be involved in osmotic adjustment since the resistant cv. NCo310 stressed calli accumulated more Cl^- than CP59-73 ones. These results suggested that the resistance to salinity in sugarcane is associated with a high K⁺, Ca²⁺ and Cl^- concentrations and a low Na⁺ concentration within cells.

Key words:  sugarcane (Saccharum sp.), salt stress, ion uptake, callus growth, long-term stress exposure.

Abbreviation

RGR, Relative growth rate; cv, cultivar; MS medium, Murashige and Skoog medium; FW, fresh weight; DW, dry weight.