Procházková Dagmar, Haisel Daniel, Wilhelmová Nad'a
Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Cell Biochem Funct. 2008 Sep-Oct;26(5):582-90. doi: 10.1002/cbf.1481.
We studied changes in antioxidant protection during ageing and senescence in chloroplasts of tobacco (Nicotiana tabacum L., cv. Wisconsin) with introduced SAG(12) promoter fused with ipt gene for cytokinin synthesis (transgenic plants with increased levels of cytokinins, SAG) or without it (control). Old leaves of SAG plants as well as their chloroplasts maintained higher physiological parameters compared to controls; accordingly, we concluded that their ageing was diverted due to increased cytokinin content. The chloroplast antioxidant protection did not decrease as well. Although antioxidant protection usually decreased in whole leaves of senescing control plants, ascorbate peroxidase (APX) and dehydroascorbate reductase (DHAR) activity, which maintained the high redox state of ascorbate, increased in chloroplasts of old control leaves.
我们研究了烟草（Nicotiana tabacum L.，品种Wisconsin）叶绿体在衰老过程中抗氧化保护的变化，这些烟草被导入了与用于细胞分裂素合成的ipt基因融合的SAG(12)启动子（细胞分裂素水平升高的转基因植物，SAG）或未导入该启动子（对照）。与对照相比，SAG植物的老叶及其叶绿体维持了更高的生理参数；因此，我们得出结论，由于细胞分裂素含量增加，它们的衰老过程发生了改变。叶绿体的抗氧化保护也没有降低。虽然在衰老的对照植物全叶中抗氧化保护通常会降低，但在老对照叶的叶绿体中，维持抗坏血酸高氧化还原状态的抗坏血酸过氧化物酶（APX）和脱氢抗坏血酸还原酶（DHAR）活性增加。
