苜蓿抗乙硫氨酸愈伤组织的筛选和特性(英文)

Selection and Characterization of Cultured Alfalfa Calluses Resistant to Ethionine

用乙硫氨酸为筛选剂 ,通过幼苗和组织培养筛选得到乙硫氨酸抗性愈伤组织。该愈伤组织在含乙硫氨酸的培养基上表现出较高的半抑制剂量和相对生长量。作为天门冬氨酸途径的产物 ,甲硫氨酸、异亮氨酸和赖氨酸在所筛选的愈伤组织中分别增加到对照的两倍多 ,但苏氨酸保持正常水平 ,另外酪氨酸、半胱氨酸和亮氨酸也有所增加 ,而在所筛选的愈伤组织中缬氨酸浓度却下降。说明在所筛选愈伤组织中存在一个以上与氨基酸合成相关的酶发生改变。同工酶分析表明 ,该愈伤组织中出现对照中没有的分子量为 44kD的超氧化物歧化酶和分子量为

Ethionine resistant cultures were isolated by screening seedlings for ethionine tolerance and selecting the calluses on an ethionine containing medium. The selected calluses exhibited higher I 50 and higher relative amount of growth in the presence of ethionine. Among the products of aspartate pathway, methionine, isoleucine and lysine each had a content twice as high as that in the control calluses, but threonine remained the same content. Unexpectedly, tyrosine, cysteine and leucine contents increased too, however valine content decreased in selected calluses. These results suggest that the presence of ethionine might have caused the alteration of more than one enzyme in the biosynthesis of amino acids in the selected calluses. New isoenzyme forms, 44 kD superoxide dismutase and 45 kD esterase, were found in the selected callus.