In vitro selection and identification of sweetpotato (<Emphasis Type="Italic">Ipomoea batatas</Emphasis> (L.) Lam.) plants tolerant to NaCl

In vitro selection of sweetpotato (Ipomoea batatas (L.) Lam.) plants tolerant to NaCl was achieved using embryogenic suspension cultures of sweetpotato cv. Lizixiang and gamma-ray induced mutation. Cell aggregates from embryogenic suspension cultures of Lizixiang were irradiated with 80 Gy gamma-ray, and 1 week after irradiation they were cultured in a selective medium containing 342 mM NaCl for in vitro selection. A total of 276 plants were regenerated from the irradiated 2,783 cell aggregates by a two-step in vitro selection procedure. After the regenerated plants were propagated into plant lines on the basal medium, they were cultured on the medium supplemented with 86, 171, 257 and 342 mM NaCl, respectively, in order to evaluate their in vitro salt tolerance. Of them 18 plant lines showed significantly higher in vitro salt tolerance than control plants. Proline and superoxide dismutase (SOD) were more accumulated in these 18 plant lines than in control plants when both were exposed to NaCl. Salt tolerance of the 18 plant lines was further evaluated with Hoalgland solution containing different concentrations of NaCl in a greenhouse. The results indicated that 3 of them had significantly better growth and rooting ability than the remaining 15 plant lines and control plants at 171 mM NaCl.