Increased NaCl-tolerance in wheat (Triticum aestivum L. andT. durum desf.) through in vitro selection

Summary Callus cultures were initiated from immature embryos of oneTriticum aestivum and threeT. durum cultivars. Growing morphogenic calli were exposed to different concentrations of NaCl (0, 0.3, 0.5, and 0.7%) added to the culture medium during two subsequent subcultures (4 wk each). The growth rate of the calli was determined by the relative fresh weight callus growth (RFWCG). The callus growth of all investigated genotypes was slightly changed in the presence of 0.3 and 0.5% NaCl, but strongly inhibited by 0.7% NaCl. Selected NaCl-tolerant clones were isolated and plants were regenerated on MS-based regeneration medium without NaCl. The regeneration capacity of the selected calli was highly reduced compared to the control. The highest number of regenerants was scored for cv. Gladiator (T. aestivum). All regenerated plants were morphologically normal and many developed to maturity and set seeds. Seedlings from the R₁ generation of selected and control plants were treated with 0.5% NaCl in vivo in liquid cultures for 6 wk. Salt tolerance of the progenies of selected plants appeared in all cultivars, but those derived from calli grown on medium with 0.7% NaCl showed the highest survival rate.T. aestivum showed higher tolerance to NaCl salinity thanT. durum.