Selection Of NaCl-tolerant Variants From Embryogenic Calli Of Maize And Analysis On Salt Tolerance

The embryogenic calli were induced from immature embryos of 9 hybrid crosses of maize and NaCl-tolerant callus variants were obtained through three generations of selections with 200mmol · L-*1 NaCl or 5.5 mmol· L-1 'Hyp.Plants were differentiated from these callus variants on regeneration medium .The selecting effects were compared between these two selection agents. Free proline content^ soluble sugar content and osmotic potential of variants and CK calli were tested, there physiology and biochemical traits relative to salt-tolerance were analysed . The main results were as followed: (l)The immature embryo 1.0 2.5mm in length was suitable to the inducement of calli. The most suitable initiation medium components were N6+ 2mg· L-12,4-D+500 mg· L-1 'pro+500 mg· L-1 CH+30g · L-1 sugar, The most suitable regeneration medium components were N6+500 mg ·L-1 pro+500 mg·L-1CH+1mg ·L-1 KT+0.5 mg ·L-1 BA+0.2 mg·L-1 NAA+30 g·L-1 sugar, (2)The selection stress of 5.5 mmol · L~'Hyp amounted to that of 200mmol · L"'NaCl,but its selection frequency was two times as much as that of the latter, and the regenerated plants from variants selected by Hyp were stronger than that from variants selected by NaCl. So, the selection effect of 5.5 mmol · L-1 Hyp was better than 200mmol · L-1 NaCl . (3)The results of selecting were as followed: Free proline content and soluble sugar content in the variants selected with 5.5 mmol ·L-1 'Hyp were 3.2 and 1.45 times as much as those in CK respectively; Free proline content and soluble sugar content in the variants selected with 200mmol · L-1 NaCl were 3.7 and 1.44'times as much as those in CK respectively, the osmotic potentials of variants selected with 5.5 mmol· L"'Hyp< the variants selected with 200mmol· L-1 NaCl