NaCl stress-induced growth, water and ions contents changes on in vitro selection of salt tolerant and salt sensitive callus of wheat (Triticum durum Desf.)

Callus cultures tolerant to NaCl were developed from eight wheat genotypes using in vitro selection techniques. The accumulation of inorganic (Na+, Cl- and K+) solutes, water content and relative fresh weight were determined in selected (tolerant and sensitive) calli after a NaCl shock in order to evaluate their implication in salt tolerance of the selected lines. No growth reduction was observed in salt-tolerant calli compared to control while a significant (P<0.05) decrease about 46.54% was observed in salt sensitive ones when both were cultivated under NaCl stress. Water content is significantly (P<0.05) high in salt-sensitive calli than salt-tolerant ones. Selected calli accumulate less K+ as compared with control. However, K+ content of salt-tolerant calli is greater than that of salt-sensitive. Accumulation of Na+ and Cl- were more important in salt-sensitive calli in comparison with salt-tolerant ones while K+ content was lower in salt-sensitive than in salt-tolerant calli when both were exposed to salt. The results indicated Na+ and Cl- exclusion combined to less K+ accumulation may play a key role in in vitro salt-tolerance in wheat calli lines obtained by in vitro selection and they could contribute mainly to counteract the negative effects of salt stress in wheat tolerant calli. Comparison of K+/Na+ ratio permitted to classify Sebou, Anouar and Tarek which are as most salt-tolerant wheat genotypes and on contrary, Marzak, Ourgh, Massa and Amjad as salt-sensitive wheat genotypes. K+/Na+ ratio can be use as a criterion of wheat genotypes classification.