Selection of salt-tolerant callus variants in maize and analysis on salt-tolerance

Chinese. 为了筛选玉米耐盐愈伤组织变异体，选用4个适于玉米组织培养基因型的幼胚为外植体，诱导出胚性愈伤组织。继代5次后，分别用200 mmol/L NaCl和5.5 mmol/L Hyp连续筛选3次，获得耐盐愈伤组织变异体，分别称为rn变异体和rh变异体，以普通继代培养基上培养的愈伤组织为对照。经一代回复培养，分别在200，250和300 mmol/L NaCl胁迫下，分别测定了rn变异体、rh变异体和对照愈伤组织存活率，胚性愈伤组织百分率，K＋、Na＋含量；在300 mmol/L NaCl胁迫下，测定了rn变异体、rh变异体和对照愈伤组织的生长量及脯氨酸含量。结果表明，rh变异体愈伤组织的分化频率高于rn变异体，Hyp的选择频率是NaCl的2倍左右；在不同浓度NaCl胁迫下，rh变异体具有较高的愈伤组织存活率和K＋、Na＋含量；在300 mmol/L NaCl胁迫下，rh变异体的生长量和脯氨酸含量均最高，表现出了较好的耐盐性。

English. In order to obtain salt-tolerant callus variants in maize, the embryogenic calli were induced from immature embryos of 4 maize genotypes that were suitable for tissue culture. After 5 generations culture, salt-tolerant calli variants were obtained through three continuous selection with 200 mmol/L NaCl and 5.5 mmol/L Hyp, called rn variant and rh variant respectively, at the same time, callus from basal subculture medium was used as CK. Through one generation back-culture, under 200, 250 and 300 mmol/L NaCl stress, callus survival ratio, embryogenic callus proportion and K＋ and, Na＋ contents of rn variant, rh variant and CK were counted or tested; growth quantity and free proline content of rn variant, rh variant and CK were tested under 300 mmol/L NaCl stress. The results showed that the differentiation frequency of rh variant was higher than that of rn variant; the selection frequency of Hyp was twice as much as that of NaCl. The rh variant had higher callus survival ratio and the contents of K＋ and Na＋ under different concentration salt stress; growth quantity and free proline content of rh variant under 300 mmol/L NaCl stress were the largest, showing stronger salt-tolerance.