烟草愈伤组织生长和衰老期间呼吸代谢的改变

Changes in Respiratory Metabolism During the Growth and Senescence of Tobacco Callus

前人(Ross和Thorpe 1973,Thorpe和Laishley 1973,Brown和Thorpe 1982)曾报道了烟草愈伤组织芽形成期间呼吸速率、线粒体活性、底物代谢途径和有关呼吸酶活性的变化。我们对烟草愈伤组织呼吸代谢的研究证明:组织分化和芽原基的形成与HMP途径运行升高相联系(毕玉蓉和梁厚果1987);

The respiratory metabolism of tobacco callus and its relation to tissue differentiation and bud primordium formation had been studied. The changes of respiratory metabolism pathway during the growth and senescence of tobacco callus were examined. The respiratory rate increased on the 6th day in culture and decreased after the 15th day. A second rise in respiratory rate of tobacco callus was observed on the 18th day in culture, which was considered to be an important phenomenon characterizing the onset of callus senescence induced by caibohydrate deficiency. According to the results of inhibition experiments with iodoacetate, malonate and Na_3PO_4, the degree of participation of HMP pathway was higher than that of EMP in callus cultured for 6～12 days. When the senescence of tobacco callus started on the 18th day in culture, the respiration of callus was markedly inhibited by iodoacetate. Obviously, EMP pathway constituted the main part of the respiratory metabolism in callus at the beginning of senescence. In the senescent callus cultured for 30 days, the contributions of EMP and HMP to total respiration decreased, but TCAC still kept its role as in growing callus. The respiration of growing callus cultured for 6～12 days was partially resistant to KCN and markedly inhibited by m-CLAM in the presence of KCN. On the 18th day in culture, the sensitivity of respiration to KCN increased significantly. It was suggested that the bulk of respiratory electron flux was mediated by cytochrome pathway at the initiation of callus senescence.