苜蓿乙硫氨酸抗性变异细胞系的筛选

Selection of Ethionine-Resistant Variant Cell Line in Alfalfa (Medicago sativa

用经返地卫星搭载诱变处理的豆科牧草紫花苜蓿 (Medicago sativa L .)干种子种植后长出的花序为外植体诱导愈伤组织 ,以 L -乙硫氨酸为筛选剂 ,通过多步正筛选途径获得了苜蓿乙硫氨酸抗性细胞系 MEr B.MEr B在脱离选择压力 9个月后 ,其对 L-乙硫氨酸的抗性 I50 (生长量半抑制时的 L-乙硫氨酸浓度 )比野生型高 14.2倍 ,表明抗性系抗性表达稳定 .抗性系还表现出对 DL-甲硫氨酸的交叉抗性和对天冬氨酸族其它几种氨基酸的抗性 .游离氨基酸含量分析表明甲硫氨酸含量明显增加 .MEr B抗性系过氧化物同功酶 (POD)和酯酶同工酶谱带 (EST)与野生型有显著差异 ,表明抗性系可能发生了基因变化并产生相应的基因产物 .

Calluses were induced from inflorescence explants of alfalfa (Medicago sativa L.) germinated from seeds treated with space conditions. A variant cell line r esistant to 2 mmol/L L ethionine (ME rB) was isolated by means of multipl e step selection from the calluses. The L ethionine resistance was stable since ME rB cell line grown on normal medium for 9 months retained high resistance to L et hionine and the I 50(concentration causing 50% growth inhibition) of ME rB was 14.2 times higher in comparison with that of the wildtype calluses. Simulta neously, ME rB exhibited cross resistance to DL methionine, as well as Threon ine, Lysine, Isoleucine, and Leucine separately or combinedly. Free amino acid a n alysis showed a significant increase in the content of methionine. The obvious d ifferences on peroxidase isoenzyme(POD) and Esterase isoenzyme(EST)electrophores is patterns between ME rB and wildtype calluses indicated the possible existenc e of changed gene products in the ethionine resistant cell line.