5,6-二氯-吲哚乙酸对烟草愈伤组织衰老的延缓作用

Retarding Effects of 5,6-Cl_2-IAA on Senescence of Tobacco Callus

5,6-二氯-吲哚乙酸对革新烟草愈伤组织生长有影响。当愈伤组织在MS_0(对照)和MS+2,4-D培养基上培养22d时,生长停滞,细胞已呈空泡状,正常的超微结构完全破坏,细胞器不复存在,愈伤组织明显褐化。但在MS+5,6-Gl_2-IAA培养基上的愈伤组织仍能正常生长,鲜重和干重下降亦明显延缓,细胞含有原生质内含物,各种细胞器的超微结构仍保持正常。此外,后者的SOD同工酶也明显不同于其它培养基上的愈伤组织,暗示5,6-Gl_2-IAA对烟草愈伤组织衰老的延缓作用可能与SOD同工酶的调节作用有关。

The effects of 5,6-Cl_2-IAA on the senescence of tobacco callus were investigated. The results show that both the flesh weight and dry weight of callus cultured on MS medium containing 5,6-Cl_2-IAA., 0.02 or 0.2 ppm, were apprently higher than those of callus incubated on MS_0 medium (control) or MS medium with 2,4-D 2 ppm for 22 days after the onset of experiment. Disruption cf ultrastructure of callus cultured on medium without 5,6-Cl_2-IAA for 22 davs was observed, which was accompanied by tissue browning. In contrast, the integrity of the ultrastructure of cells in callus cultured on medium supplemented with 5,6-Cl_2-IAA was kept. For example, the integrity of nucleus, mitochondria, endoplasmic reticulum and ribosome was protected by this substance against degradation during the senescence of tissues and tissues browning was also prevented. These findings indicated that 5,6-Cl_2-IAA had strong activity in maintaining normal growth of callus and delaying the senescence of callus during tissue culture. In addition, SOD isoenzymes in callus incubated on a medium with 5,6-Cl_2-IAA differed significantly from those in callus cultured on MS_0 medium and MS medium supplemented with 2,4-D 2 ppm, implying that the promoting effects of 5,6-Cl_2-IAA on the activity of SOD isoenzvmes might be related to its effect in delaying cahus senescence.